CA2039687C - Method for operation of flash smelting furnace - Google Patents
Method for operation of flash smelting furnaceInfo
- Publication number
- CA2039687C CA2039687C CA002039687A CA2039687A CA2039687C CA 2039687 C CA2039687 C CA 2039687C CA 002039687 A CA002039687 A CA 002039687A CA 2039687 A CA2039687 A CA 2039687A CA 2039687 C CA2039687 C CA 2039687C
- Authority
- CA
- Canada
- Prior art keywords
- oxygen
- concentrate
- blowing tube
- auxiliary fuel
- settler
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000003723 Smelting Methods 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 133
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 133
- 239000001301 oxygen Substances 0.000 claims abstract description 133
- 239000012141 concentrate Substances 0.000 claims abstract description 101
- 238000006243 chemical reaction Methods 0.000 claims abstract description 67
- 238000007664 blowing Methods 0.000 claims abstract description 53
- 239000000446 fuel Substances 0.000 claims abstract description 33
- 239000000428 dust Substances 0.000 claims abstract description 25
- 239000002893 slag Substances 0.000 claims abstract description 23
- 239000002994 raw material Substances 0.000 claims description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- 238000002485 combustion reaction Methods 0.000 claims description 19
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 17
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 16
- 229910052742 iron Inorganic materials 0.000 claims description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 239000010949 copper Substances 0.000 claims description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 239000011701 zinc Substances 0.000 claims description 2
- 235000008504 concentrate Nutrition 0.000 description 87
- 230000001965 increasing effect Effects 0.000 description 11
- 239000000295 fuel oil Substances 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 239000002245 particle Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 238000011017 operating method Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- -1 iron metals Chemical class 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 2
- 230000003028 elevating effect Effects 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229960005419 nitrogen Drugs 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000011133 lead Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B15/00—Obtaining copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces
- F27B3/10—Details, accessories or equipment, e.g. dust-collectors, specially adapted for hearth-type furnaces
- F27B3/22—Arrangements of air or gas supply devices
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Engineering & Computer Science (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Gas Burners (AREA)
Abstract
A method for operation of a flash smelting furnace comprising a reaction shaft, a settler connected at one end thereof to the lower portion of the reaction shaft and having a slag discharge port and a matte discharge port disposed on the side thereof, an uptake connected to the other end of the settler and at least one concentrate burner disposed to at least one of the top of the reaction shaft and the ceiling of the settler, in which the concentrate burner comprises at least a concentrate shoot, an oxygen blowing tube inserted in the concentrate shoot and an auxiliary fuel burner inserted into the oxygen blowing tube. In this method, the lower end of the oxygen blowing tube is protruded downward to lower than the lower end of the concentrate shoot and an amount of oxygen at least greater than that required for the auxiliary fuel is blown as an industrial oxygen by way of the oxygen blowing tube into the furnace. Oxygen efficiency can be improved remarkably while the rate of dust occurrence can be re-duced.
Description
. 2039687 METHOD FOR OPERATION OF FLASH SMELTING FURNACE
BACKGROUND OF THE INVENTION
Field of the Invention The present invention concerns a method for operation of a flash smelting furnace, in particular, for smelting non-iron metals.
Description of the Prior Art A flash smelting furnace has been known as one of refining furnaces using sulfide concentrates as a raw material. Fig. 3 shows an example of a structure of the flash smelting furnace of this kind, which is referred to as an ~utokumpu type flash smelting furnace. In the figure, the flash smelting furnace 1 basically comprises a reaction shaft 3 having a concentrate burner 2 disposed at the top, a settler 6 connected at one end thereof to the lower portion of the reaction shaft 3 and having a slag discharge port 4 and a matte discharge port 5 disposed on the side thereof and an uptake 7 connected to the other end of the settler 6. In the operation of such an ~uto-kumputype flash smelting furnace, a smelting raw material 8 such as a sulfide concentrate, a flux and an auxiliary fuel is at first blown together with a portion of a reaction air by way of the concentrate burner 2 into the reaction .
shaft 3. In the reaction shaft 3, sulfur and iron as the combustible components of the smelting raw material 8 heated by the combustion of the auxiliary fuel are brought into reaction with the reaction air 9, which is also heated, and then accumulated in a molten state in the settler 6. Further, the melt accumulated in the settler 6 as a hearth is separated by the difference of the specific gravity of the ingredients thereof into a matte 10 con-sisting of a mixture of Cu2S and FeS and a slag 11 mainly composed of 2FeO SiO2. The slag 11 is discharged from the slag discharge port 4 and introduced into an electric slag cleaning furnace 1~, while the matte 10 is properly dis-charged from the matte discharge port 5 in accordance with a demand from a converter in the subsequent step. The slag 11 entering the electric slag cleaning furnace 12 is kept to be heated by a heat generated from electric cur-rent supply from an electrode 13 and mixed with ore lumps, flux lumps, etc. charged as required to the electric slag cleaning furnace 12, in which the copper component is deposited further to the bottom of the furnace and only the slag containing a slightly remaining copper component is discharged from the outlet 14 to the outside of the furnace. A waste gas 15 at high temperature emanated in the reaction shaft 3 is sent by way of the settler 6 and the uptake 7 and then cooled by a waste heat boiler 16.
2039~87 In the utokumpu type flash smelting furnace, since the control for the oxidation degree of the smelting raw-material and the control for the smelting temperature can be conducted independently of each other, it is suitable to refining plants using commercial ores in which the compositions of the raw materials vary inevitably.
However, in such a conventional flash smelting furnace, there has been a problem that no sufficient heat calorie required for melting the smelting raw mate-rial 8 can be obtained. That is, the residence time for the particles of the smelting raw material 8 blown by way of the concentrate burner 2 is usually about one second, during which the particles have to be melted by heating to the ignition temperature thereof and being brought into reaction with oxygen in the reaction air 9. Then, although it is necessary to preheat the reaction air 9 -to the ignition temperature quickly, the upper limit for the temperature of the reaction air 9 is restricted to 400 - 500 C in view of the relation with the heat resistant temperature of materials for the facilities of the smelting furnace and no sufficient pre-heating can be applied, with a result that the rate of dust generation is increased, as well as the oxygen utilization ratio, that is, oxygen efficiency is inevitably lowered.
In view of the above, a method of using an oxygen - 2039~87 enriched air as a reaction air has been put to practical use in order to overcome such a problem. For instance, according to a device disclosed in Japanese Patent Publi-cation Sho 59-41495, improvement is intended for the oxygen efficiency, while taking notice on the high reactivity between an industrial oxygen and a sulfide concentrate by blowing an oxygen-enriching oxygen entirely or partially into a concentrate shoot, while supplying air or an oxygen enriched air from a venturi portion of a concentrate burner, thereby uniformly mixing and dispersing the smelting raw material such as the sulfide concentrate and oxygen.
On the other hand, if the mixing between the smelting raw material blown from the concentrate burner 2 into the reaction shaft 3 of the furnace 1 and an oxygen-enriching oxygen or oxygen-enriched reaction air is insufficient, the utilization efficiency of oxygen reacting with the smelting raw material, that is, the oxygen efficiency is lowered. If the oxygen efficiency is low, it is necessary to supply an oxygen-enriching oxygen or oxygen-enriched reaction air in an amount than required, which leads to the increase of an auxiliary fuel for elevating the tempe-rature of the reaction air supplied in excess and to the increase of the rate of dust generation along with the increase of the amount of waste gases.
For overcoming such a problem, there can be mentioned 203q687 prior art in, for example, Japanese Utility Model Laid-Open Hei 1-78161 and Hei 1-78162 and the Japanese Patent Laid-Open Hei 2-230234.
Japanese Utility Model Laid Open Hei 1-78161 and Hei 1-78162 describe a concentrate burner comprising an air supply tube, a venturi portion concentrically joined to the lower surface at one end of the air supply tube and a concentrate shoot vertically penetrating the end of the air supply tube from above and extended concentrically to the venturi portion, in which a reaction air supplied f~om the air supply tube passing between the concentrate shoot and the venturi portion is blown into the top of the reaction shaft (hereinafter referred to as a conventional concentrate burner), wherein one or two blow control plates are disposed in the air supply tube in adjacent with the venturi portion so that the reaction air is blown uniformly from the venturi portion.
Further, in Japanese Patent Laid Open No. Hei 2-230234, at least one set of air supply nozzles are disposed near the middle portion of a reaction shaft each at a 180- symmetrical position with respect to a vertical line passing through the center of the reaction shaft, such that the axial blowing direction of each of the nozzles aligns with the vertical line, and each of the nozzles is made rotatable within a vertical plane includ-2~39687 ing the axial blowing direction of the nozzle. A portionof a reaction air is blown from the nozzles to form a turbulent flow over the entire region in the reaction shaft, so that the smelting raw material flown from the concentrate burner into the reaction shaft is uniformly dispersed in the reaction air and the residence time thereof in the reaction shaft is prolonged, by which the smelting raw material such as the concentrate ore and the reaction air can be effectively brought into reaction and the oxygen efficiency of the reaction air can be improved further, with a result that the rate of dust generation can be reduced and the formation of unmelts can be pre-vented.
However, in the device as disclosed in Japanese Patent Publication Sho 59-41495, since oxygen for oxygen enrich-ment is jetted into a concentrate shoot, sulfide concen-trates are brought into reaction with oxygen in the con-centrate shoot and fused to the inside of the shoot to clog the concentrate shoot thereby making continuous operation impossible. Further, in this device, since concentrate particles are sufficiently suspended in an oxygen gas stream, satisfactory reaction is taken place in the furnace. However, since the gas stream does not spread, concentrate particles are liable to be discharged together with exhaust gases containing S02 generated by combustion to the outside of the furnace, which brings about a disadvantage that not only the rate of dust gener-ation can not be reduced but also the generation rate is rather increased depending on the operating conditions.
The device as disclosed in Japanese Utility Model Laid-Open Hei 1-78161 and Hei 1-78162 comprise a flow control plate disposed for making the uniform blowing of the reaction air from the venturi portion in the conven-tional concentrate burner and it can sufficiently enjoy the performance of the conventional concentrate burner.
However, the performance of the conventional concentrate burner is only that the rate of dust generation is more than 9% and the oxygen efficienc~ is less than 80%, and no better performance can be expected.
According to the examples in Japanese Patent Laid-Open Hei 2-230234, it has been reported that the rate of dust generation is 5.8% and the oxygen efficiency is 100%
as the best result obtained in the operation. Then, it is apparent that the flash smelting furnace and the operating method according to this invention are excellent over the flash smelting furnace and the operating method using the conventional concentrate burner. However, according to the study made subsequently, it has been apparent that if the ratio of the silicate ore added other than the sulfide concentrate as the smelting raw material is increased in the operation o~ t~e example, although the ~ate o~ dust gener~tion did not change so much but the ox~en ef~iciency was reduced. This ls assumed to be ~ttributable to the ~ollowing rea~on~.
In accordance wl~h this ope~ting method, since a portion of the reactlon gas is blow~ from an a~r supply nozzle and h~ agains~ a ~et stream ~ormed by the concen-t~ate burner, to form a turbulent flow spreading over the entire re~ion in the re~ct~on sha~t, the smelting raw material blown to~e~her with the auxi~iar~ fuel and the reactlo~ air ~ro~ the conce~trate bu~er into the reaction s~aft is uniformly dispersed 1~ the reactio~ air. In this case, silicate ore, powdery iron concentrat~, copper slag, dust or ~e like, othe~ ~an the sulfide concen~rate added as ~he smelting raw materlal are ~on-combustible sub-stances, whi~h hinder the combustion of the concentrate ore in the reactlon sha~t. Amo~ all. since the silicate ore ~s the main ~ngredient SlO2 the melting point oP
which ls as high as 1720'C. it f5 apparent t~at the com-bustibility of the concent~ate ore is greatly hindered.
ln this operatimg method, since the concentrate ore under com~ustion and silicious sa~d are unifo~mly dispersed in the reaction sh~ft as the ra~o of ~he silicate ore added is inc~eased, th~ silicate ore ~ts as if it were a pow-de~y fire exti~guishing a~e~. This results ln the lowé~-2039~87 ing of the temperature of the concentrate particles under combustion,which suppresses the oxidizing reaction of the concentrate ore itself to reduce the oxygen efficiency.
OBJECT OF THE INVENTION
In view for the foregoing problems, it is an object of the present invention to provide an operating method for a flash smelting furnace capable of remarkably improving the oxygen efficiency and reducing the rate of dust gene-ration in a flash smelting furnace for non-iron metals using an oxygen-enriched air as a reaction air.
SU~IARY OF THE INVENTION
According to the invention there is provided a method of operating a flash smelting furnace having a reaction shaft, a settler having first and second opposite ends connected at said first end to a lower portion of the reaction shaft, said settler having a slag discharge port and a matte discharge port disposed on a side of the settler, an uptake connected to said second end of said settler, and at least one concentrate burner disposed at a top of said reaction shaft or a ceiling of said settler, wherein said concentrate burner comprises at least a concentrate chute, an oxygen blowing tube inserted in said concentrate `- 2û39687 chute, and an ~llxili~ry fuel burner inserted into said oxygen blowing tube, and wherein a lower end of the oxygen blowing tube protrudes downwards to a point below a lower end of the concentrate chute, which method comprises feeding a smelting raw material through said concentrate chute, supplying auxiliary fuel to said auxiliary fuel burner and providing an amount of oxygen in excess of that required for combustion of the auxiliary fuel by blowing industrial oxygen into the furnace through said oxygen blowing tube.
In another aspect of the present invention, all the amount of oxygen required for the combustion of the smelting raw material and the auxiliary fuel is blown into the furnace as an industrial oxygen by way of the oxygen blowing tube.
In a further aspect of the present invention as described above, the lower end of the ~llxili~ry fuel burner is constituted such that it is at an identical level with that for the lower end of the oxygen blowing tube.
In accordance with the constitution as described above, among the smelting raw materials supplied from the concentrate shoot, self-combustible sulfide concentrates such as copper, nickel, zinc and lead are rapidly heated and ignited by radiation heat from a reactor wall.
, ~
an exhaust gas at high temperature or a flame formed by an auxiliary fuel burner. Since an industrial oxygen in an amount required for the combustion of the auxiliary fuel is blown by way of the oxygen blowing tube, the ignited sulfide concentrate is rapidly brought into reaction with the industrial oxygen supplied from the oxygen blowing tube to form a matte and a slag, in which the matte and the slag at high temperature collide against each other to increase the size of particles during falling in the reaction shaft, as well as they also collide against and melt non-combustible substances such as silicate ore, copper slag, powdery iron concentrate and dust added as the smelting raw material. Further, a portion of the non-combustible substances is melted also by the radiation heat due to the combustion of the sulfide concentrate or an exhaust gas at high temperature. In this case, since the industrial oxygen supplied from the oxygen blowing tube means such an oxygen usually at 90% or higher oxygen concentration, the oxidizing reaction (combustion) of the sulfide concentrate is more rapid as compared with the oxidizing reaction with air or oxygen-enriched air. Since air or oxygen-enriched air contains a lot of inert nitro-gen other than oxygen, this hinders the reaction between the sulfide concentrate and oxygen. ~urther, in the case of using the industrial oxygen, the temperature of the exhaust gas mainly composed of S02 released upon combus-tion of the sulfide concentrate is higher than the temper-ature of an exhaust gas in a case of using oxygen or oxygen-enriched air, since there is no requirement for elevating the temperature of nitrogen or the like.- with the functions as described above, since the smelting raw material supplied in the reaction shaft causes efficient reaction with the industrial oxygen, flash smelting at a low rate of dust generation and at high oxygen efficiency is possible.
In particular, if the entire amount of oxygen required for the combustion of the smelting raw material and the auxiliary fuel is blown as an industrial oxygen by way of the oxygen blowing tube into the furnace, it is possible to reduce the rate of dust generation and increase the oxygen efficiency even if the addition ratio of the non combustible substances other than the sulfide concentrate as the smelting raw material is increased, with the reasons described above.
Further, if the lower end of the auxiliary fuel burner is constituted so as to be in the same level as that for the lower end of the oxygen blowing tube, the best result is obtained. This is attributable to that a vigorous heavy oil combustion flame is formed near the lower end and the reaction of the smelting raw material ~, passing through the flame is completed within an extremely short period of time, thereby enabling to extend a time for increasing the size of particles by the collision between each other in the reaction shaft.
DESCRIPTION OF THE ACCOMPANYING DRAWINGS
These and other objects, as well as advantageous features of the present invention will become apparent by reading the following descriptions for preferred embodi-ments with reference to the accompanying drawings, wherein Fig. 1 is a schematic view for a concentrate burner of a flash smelting furnace used in Example 1;
Fig. 2 is a schematic view for a concentrate burner of a flash smelting furnace used in Examples 2 and 3;
and Fig. 3 is a view illustrating a constitution of a conventional flash smelting furnace.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
- The present invention will now be described more in details with reference to examples illustrated in the drawings.
Example 1 Fig. 1 is a schematic view for a concentrate burner .
2' of a flash smelting furnace used in this example, in which a wind box 17 has a restricted portion 17a and an opening 17b diverged downwardly, a concentrate shoot 18 is suspended in the central portion of the window box 17 such that the lower end is situated slightly below the re-stricted portion 17a, an oxygen blowing tube 19 concentri-cally penetrates the concentrate shoot 18 and has a dis-persion cone 20 around the outer periphery at the lower end thereof that protrudes downward to lower than the top end of the concentrate shoot 18, and an auxiliary fuel burner 21 concentrically penetrates the oxygen blowing tube 19 with the lower end thereof being situated at the same level as that for the lower end of the oxygen blowing tube 19. Test operation was conducted by using a medium scale test furnace with a concentrate processing capacity of about 0.8 t/h and having a reaction shaft 3 equipped with such a concentrate burner 2' at the top and having 1.5 m inner diameter and 4.0 m height and a settler 6 having 1.5 m inner diameter and 5.~5 m length (refer to Fig. 3) for four days under the conditions shown in Table 1 below respectively.
.
Table 1 Conditions for Test Operation No.1 No.2 No.3 No.4 Amount of concentrate treated t/h 0.8 0.8 0.8 0.8 Amount of silicate ore treated t/h 0.07 0.07 0.07 0.08 Amount of heavy oill/h 23 23 23 23 Amount of Air Nm3/h 425 425 425 425 Amount of industrial oxygen (90%) Nm3/h 134 134 134 134 Amount of oxygen from oxygen blowing tube (90%) Nm3/h 0 54 134 134 In Table 1, the amount of industrial oxygen means the amount of industrial oxygen used as enriching oxygen, and the amount of oxygen from the oxygen blowing tube means such an amount of oxygen, among the industrial oxygen, that was blown from the oxygen blowing tube 19 into the furnace. In the test operation No. 1 (Comparative Example 1), industrial oxygen and air were mixed and, the entire amount was supplied from the wind box 17. In the test operation No. 2, oxygen in an amount only required for the combustion of heavy oil as an auxiliary fuel (54 Nm3/h) was blown from the oxygen blowing tube 19 into the furnace, while the remaining oxygen was mixed with air and supplied from the window box 17 into the furnace. In the test 20~9B87 operation No. 3, the entire amount of the industrial oxygen (134 Nm3/h) was blown from the oxygen blowing tube 19 into the furnace. In thé'se cases~.(No.l --No.3),~
the lower end of the auxiliary fuel burner 21 was adjusted such that it protruded downwardly to lower than the top end of the oxygen blowing tube 19. Further, in the test operation No. 4, the operati~g conditions were the same as those in the case of the test operation No. 3 excepting that the lower end of the auxiliary fuel burner 21 was situated so as to be at the same level as the lower end of the oxygen blowing tube 19.
The results for each of the test operations No. 1 -No. 4 are be shown in the following Table 2.
Table 2 Result No.l No.2 No.3 No.4 Matte grade -- % 56.8 55.4 69.7 68.9 Temperature of slag C 1226 1235 1277 1289 Rate of dust generation % 15.6 11.3 14.3 10.8 Oxygen efficiency % 82.0 84.5 95.1 98.4 As apparent from the results shown in Table 2, the rate of dust generation is reduced and the oxygen effi-ciency is improved by blowing oxygen in an amount more .
' 20396s7 than that for the auxiliary fuel through the oxygen blow-ing tube 19. That is, ignition and combustion of the auxiliary fuel is usually conducted prior to ignition and combustion of the fine concentrate and, when the amount of industrial oxygen blown from the oxygen blowing tube 19 is increased at least greater than the amount of oxygen required for the combustion of the auxiliary fuel, the concentrate and oxygen cause a vigorous reaction in the high oxygen concentration portion in the thus resultant gas stream, by which the reaction time as a whole can be shortened remarkably.
Particularly, in a case of the test operation No. 4, best operating result can be obtained by not only blowing the entire amount of the enriching oxygen (134 Nm3/h) from the oxygen blowing tube 19 into the furnace but also situating the lower ends for the oxygen blowing tube 19 and the auxiliary fuel burner 21 at an identical level.
with the reasons described below. Since a vigorous com-bustion flame of heavy oil is formed near the top ends of the oxygen blowing tube 19 and the auxiliary fuel burner 21, and the smelting raw material passing in the flame is instantly heated to complete the reaction of the smelting raw material within an extremely short period of time and, as a result, the time for increasing the grain size of particles due to their collision to each other in the reaction shaft 3 can be extended.
Further, the following Tables 3 and 4 show the operati~ conditions and the operating results for the test operation No. 5, in which the lower ends of the oxygen blowing tube 19 and the auxiliary fuel burner 21 were adjusted to an identical level, and only the industrial oxygen was used as the reaction air and the entire amount was blown from the oxygen blowing tube 19 into the furnace in the medium-scaled test furnace described above.
Table 3 20~9687 Conditions for Test Operation No.5 Amount of concentrate treated t/h 0.8 Amount of silicate ore treated t/h 0.07 Amount of heavy oill/h 8 Amount of Air Nm3/h 0 Amount of industrial oxygen (90%) Nm3/h 198 Amount of oxygen from oxygen blowing tube (90%) Nm3/h 198 Table 4 Result No.5 Matte grade~ % 63.3 Temperature of slag C 1299 Rate of dust generation % 4.8 Oxygen efficiency % 100 According to the test operation No. 5, it was possible to remarkably reduce the rate of dust generation and, in particular, increase the oxygen utilization efficiency to 100%.
In this embodiment, the oxygen efficiency can be 2~39~87 improved, in which the dispersion co 20 in the flash smelting furnace uniformly disperses the smelting raw material to prevent the occurrence of a so-called heap (lump of unmelted product).
In a case of using the same conditions as those for the test operation No. 5 and blowing oxygen from the concentrate shoot 18 instead of the oxygen blowing tube 19 into the furnace, the concentrate was burnt at the inside of the concentrate shoot 18 to clog the concentrate shoot 18 within about 2 hours after the start of the test opera-tion.
Example 2 Fig. 2 is a schematic view for a concentrate burner 2" of a flash smelting furnace used in this example 2 consti-tuted by removing the wind box 17 from the concentrate burner of Example 1 (Fig. 1). Then, operation was con-ducted under the conditions shown in the following Table 1 by using asmall-sized experimental flash smelting furnace comprising a reaction shaft 3 having such a concentrate burner 2" disposed at the top and having an inner diameter of 1.5 m and a height of 2.5 m from the ceiling to the melted surface of the settler and a settler 6 having an inner diameter of 1.5 m and a length of 5.25 m, with the amount of the concentrate treated of about 0.8 t/h and the 2~39~87 aimed matte grade - as 50%. In the test operation No.
1, a flame was formed by supplying heavy oil at a rate of 7 l/h from the auxiliary fuel burner. In the test opera-tion No. 2, the heavy oil was not supplied. The opera-tions were conducted for three days and two days respec-tively.
Table l Test Operation No. 1 No. 2 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.868 0.797 Amount of silicate ore treated t/h 0.067 0.057 Amount of heavy oil l/h 7.0 0 Amount of Air supplied Nm3/h 0 0 Amount of industrial oxygen (90% 2) Nm3/h 144.1 139.9 The results are shown in the following Table 2.
Table 2 2039~87 Result No.1 No. 2 Matte grade ~ % 48.4 53.0 Temperature of slag C 1276 1304 Rate of dust generation % 4.3 6.7 Oxygen efficiency % 99.5 98.2 Comparative Example 2 Operation was conducted for two days under the condi-tion No. 3 shown in the Table 3 by using the same small-scaled experimental flash smelting furnace as that in Example 2 having a conventional concentrate burner disposed at the top, with the aimed matte grade as 50%. Further, operation was conducted for three days under the condition No. 4 shown in the following Table 3, with the aimed matte grade as 55 %, by using the same small-sized experimental flash smelting furnace as that in Example 2 having a concentrate burner disposed at the top and a set of air supply nozzles disposed near the central portion for the side wall thereof shown in Japanese Patent Laid-Open Hei 2-230234. In the following Table 3, L represents the height for the reaction shaft and I represents a distance from the ceiling of the reaction shaft to the air supply nozzle.
Table 3 2~9~87 Test Operation No. 3 No. 4 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.772 0.767 Amount of silicate ore treated t/h 0.07 0.081 Amount of heavy oil l/h 12.3 7.1 Amount of Air supplied Nm3/h 455.4 o Amount of industrial oxygen (90% 2) Nm3/h 104-.8 90.4 Air supply nozzle condition:
Amount o~ air supplied Nm3/h - 446.0 Blowing rate m/sec - 49.3 I/L - 0.323 Number of air supply nozzle - 2 Blowing angle - horizontal The results are shown in the following Table 4.
Table 4 Result No.3 No. 4 Matte grade % 53.8 54.2 Temperature of slag C 1315 1274 Rate of dust generation % 10.0 5.3 Oxygen efficiency % 78.3 95.3 As apparent from the comparison for the results 2 0 3 9 ~ 8 7 between Example 2 and Comparative Example 2, it can be seen that the operation method according to the present invention enables an operatin~ with lower rate of dust generation and higher oxygen efficiency than those in the conventional flash smelting furnace.
Example 3 An operation was conducted under the operating condi-tions as shown in the following Table 1 by using the same small-sized experimental flash smelting furnace as in Example 2, with the aimed -matte grade being 50%. In the test operation No. 1, the addition rate of silicate ore to the concentrate was increased and,in thé test operation No. 2,siliciou~ sand and powdery iron concen-trate were added to increase the addition rate of the non-combustible substances, in which operations were conducted for two days and three days respectively.
2039~87 -Table 1 Test Operation No. 1 No. 2 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.7880.809 Amount of silicate ore treated t/h 0.1170.052 Amount of powdery iron concentrate treated t/h 0 0.077 Amount of heavy oil l/h 7.1 7.0 Amount of Air supplied Nm3/h 0 0 Amount of industrial oxygen (90% 2) Nm3/h 145.7 143.3 The results are shown in the following Table 4.
Table 2 Result No.1 No.2 Matte grade % 52.6 52.5 Temperature of slag C 1254 1290 Rate of dust generation % 5.7 4.7 Oxygen efficiency % 99.2 99.8 2039~87 Comparative Example 3 Operation was conducted by a small-sized experimental smelting furnace having a concentrate burner disposed at the top and a pair of air supply nozzles disposed near the central portion on the side wall thereof under the operatinq conditions shown in the following Table 3 with the aimed mat~e grade - being 55% in the same way as the test operation No. 4 in Comparative Example 2. In the test operation No. 3, the addition ratio of silicate ore to the concentrate was increased and, in the test operation No.
4, the silicate ore and the powdery iron concentrate were added to increase the addition ratio of the non-combusti-ble substances, in which operations were conducted for two days and three days respectively. In the following Table 3, L represents the height of the reaction shaft and I
represents a distance from the ceiling of the reaction shaft to the air supply nozzle.
Table 3 Test Operation No. 3 No. 4 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.797 0.730 Amount of silicate ore treated t/h 0.131 0.073 Amount of powdery iron concentrate treated t/h O 0.091 Amount of heavy oil l/h 7.0 7.0 Amount of Air supplied Nm3/h 0 0 Amount of industrial oxygen (90% 2) Nm3/h 99.5 102.0 Condition for air supply nozzle:
Amount of air supplied Nm3/h 504.4 475.8 Blowing rate m/sec 55.7 52.6 I/L 0.323 0.323 Number of air supply nozzle 2 2 Blowing angle horizontal horizontal The results are shown in the following Table 4.
.
Table 4 Result No.3 No. 4 Matte grade % 52.5 53.5 Temperature of slag C 1275 1247 Rate of dust generation % 5.5 5.9 Oxygen efficiency % 85.4 80.6 As apparent from the comparison of the results between Example 3 and Comparative Example 3, it can be seen that the operati~ method according to the present invention can provide a flashing smelting furnace opera-tion at low rate of dust generation and high oxygen effi-ciency even if the addition ratio of the non-combustible substances to the concentrate is increased, which was impossible by the conventional operating method.
When the operation was conducted by using the same small-sized experimental flash melting furnace as in the test operation No. 3 of Comparative Example 2 equipped with a conventional concentrate burner, under the condi-tions for the concentrate burner, with the amount of concentrate treated as 0.823 t/h and the amount of sili-cate ore treated as 0.115 t/h, unmelted matters were deposited on the molten surface under the reaction shaft and operation was possible only for four hours.
As has been described above, the operating method for flash smelting furnace according to the present invention can provide a practically important advantage capable of remarkably increasing the oxygen efficiency and reducing the rate of dust generation in a flash smelting furnace for non-iron metals using an oxygen-enriched air as the reaction air.
BACKGROUND OF THE INVENTION
Field of the Invention The present invention concerns a method for operation of a flash smelting furnace, in particular, for smelting non-iron metals.
Description of the Prior Art A flash smelting furnace has been known as one of refining furnaces using sulfide concentrates as a raw material. Fig. 3 shows an example of a structure of the flash smelting furnace of this kind, which is referred to as an ~utokumpu type flash smelting furnace. In the figure, the flash smelting furnace 1 basically comprises a reaction shaft 3 having a concentrate burner 2 disposed at the top, a settler 6 connected at one end thereof to the lower portion of the reaction shaft 3 and having a slag discharge port 4 and a matte discharge port 5 disposed on the side thereof and an uptake 7 connected to the other end of the settler 6. In the operation of such an ~uto-kumputype flash smelting furnace, a smelting raw material 8 such as a sulfide concentrate, a flux and an auxiliary fuel is at first blown together with a portion of a reaction air by way of the concentrate burner 2 into the reaction .
shaft 3. In the reaction shaft 3, sulfur and iron as the combustible components of the smelting raw material 8 heated by the combustion of the auxiliary fuel are brought into reaction with the reaction air 9, which is also heated, and then accumulated in a molten state in the settler 6. Further, the melt accumulated in the settler 6 as a hearth is separated by the difference of the specific gravity of the ingredients thereof into a matte 10 con-sisting of a mixture of Cu2S and FeS and a slag 11 mainly composed of 2FeO SiO2. The slag 11 is discharged from the slag discharge port 4 and introduced into an electric slag cleaning furnace 1~, while the matte 10 is properly dis-charged from the matte discharge port 5 in accordance with a demand from a converter in the subsequent step. The slag 11 entering the electric slag cleaning furnace 12 is kept to be heated by a heat generated from electric cur-rent supply from an electrode 13 and mixed with ore lumps, flux lumps, etc. charged as required to the electric slag cleaning furnace 12, in which the copper component is deposited further to the bottom of the furnace and only the slag containing a slightly remaining copper component is discharged from the outlet 14 to the outside of the furnace. A waste gas 15 at high temperature emanated in the reaction shaft 3 is sent by way of the settler 6 and the uptake 7 and then cooled by a waste heat boiler 16.
2039~87 In the utokumpu type flash smelting furnace, since the control for the oxidation degree of the smelting raw-material and the control for the smelting temperature can be conducted independently of each other, it is suitable to refining plants using commercial ores in which the compositions of the raw materials vary inevitably.
However, in such a conventional flash smelting furnace, there has been a problem that no sufficient heat calorie required for melting the smelting raw mate-rial 8 can be obtained. That is, the residence time for the particles of the smelting raw material 8 blown by way of the concentrate burner 2 is usually about one second, during which the particles have to be melted by heating to the ignition temperature thereof and being brought into reaction with oxygen in the reaction air 9. Then, although it is necessary to preheat the reaction air 9 -to the ignition temperature quickly, the upper limit for the temperature of the reaction air 9 is restricted to 400 - 500 C in view of the relation with the heat resistant temperature of materials for the facilities of the smelting furnace and no sufficient pre-heating can be applied, with a result that the rate of dust generation is increased, as well as the oxygen utilization ratio, that is, oxygen efficiency is inevitably lowered.
In view of the above, a method of using an oxygen - 2039~87 enriched air as a reaction air has been put to practical use in order to overcome such a problem. For instance, according to a device disclosed in Japanese Patent Publi-cation Sho 59-41495, improvement is intended for the oxygen efficiency, while taking notice on the high reactivity between an industrial oxygen and a sulfide concentrate by blowing an oxygen-enriching oxygen entirely or partially into a concentrate shoot, while supplying air or an oxygen enriched air from a venturi portion of a concentrate burner, thereby uniformly mixing and dispersing the smelting raw material such as the sulfide concentrate and oxygen.
On the other hand, if the mixing between the smelting raw material blown from the concentrate burner 2 into the reaction shaft 3 of the furnace 1 and an oxygen-enriching oxygen or oxygen-enriched reaction air is insufficient, the utilization efficiency of oxygen reacting with the smelting raw material, that is, the oxygen efficiency is lowered. If the oxygen efficiency is low, it is necessary to supply an oxygen-enriching oxygen or oxygen-enriched reaction air in an amount than required, which leads to the increase of an auxiliary fuel for elevating the tempe-rature of the reaction air supplied in excess and to the increase of the rate of dust generation along with the increase of the amount of waste gases.
For overcoming such a problem, there can be mentioned 203q687 prior art in, for example, Japanese Utility Model Laid-Open Hei 1-78161 and Hei 1-78162 and the Japanese Patent Laid-Open Hei 2-230234.
Japanese Utility Model Laid Open Hei 1-78161 and Hei 1-78162 describe a concentrate burner comprising an air supply tube, a venturi portion concentrically joined to the lower surface at one end of the air supply tube and a concentrate shoot vertically penetrating the end of the air supply tube from above and extended concentrically to the venturi portion, in which a reaction air supplied f~om the air supply tube passing between the concentrate shoot and the venturi portion is blown into the top of the reaction shaft (hereinafter referred to as a conventional concentrate burner), wherein one or two blow control plates are disposed in the air supply tube in adjacent with the venturi portion so that the reaction air is blown uniformly from the venturi portion.
Further, in Japanese Patent Laid Open No. Hei 2-230234, at least one set of air supply nozzles are disposed near the middle portion of a reaction shaft each at a 180- symmetrical position with respect to a vertical line passing through the center of the reaction shaft, such that the axial blowing direction of each of the nozzles aligns with the vertical line, and each of the nozzles is made rotatable within a vertical plane includ-2~39687 ing the axial blowing direction of the nozzle. A portionof a reaction air is blown from the nozzles to form a turbulent flow over the entire region in the reaction shaft, so that the smelting raw material flown from the concentrate burner into the reaction shaft is uniformly dispersed in the reaction air and the residence time thereof in the reaction shaft is prolonged, by which the smelting raw material such as the concentrate ore and the reaction air can be effectively brought into reaction and the oxygen efficiency of the reaction air can be improved further, with a result that the rate of dust generation can be reduced and the formation of unmelts can be pre-vented.
However, in the device as disclosed in Japanese Patent Publication Sho 59-41495, since oxygen for oxygen enrich-ment is jetted into a concentrate shoot, sulfide concen-trates are brought into reaction with oxygen in the con-centrate shoot and fused to the inside of the shoot to clog the concentrate shoot thereby making continuous operation impossible. Further, in this device, since concentrate particles are sufficiently suspended in an oxygen gas stream, satisfactory reaction is taken place in the furnace. However, since the gas stream does not spread, concentrate particles are liable to be discharged together with exhaust gases containing S02 generated by combustion to the outside of the furnace, which brings about a disadvantage that not only the rate of dust gener-ation can not be reduced but also the generation rate is rather increased depending on the operating conditions.
The device as disclosed in Japanese Utility Model Laid-Open Hei 1-78161 and Hei 1-78162 comprise a flow control plate disposed for making the uniform blowing of the reaction air from the venturi portion in the conven-tional concentrate burner and it can sufficiently enjoy the performance of the conventional concentrate burner.
However, the performance of the conventional concentrate burner is only that the rate of dust generation is more than 9% and the oxygen efficienc~ is less than 80%, and no better performance can be expected.
According to the examples in Japanese Patent Laid-Open Hei 2-230234, it has been reported that the rate of dust generation is 5.8% and the oxygen efficiency is 100%
as the best result obtained in the operation. Then, it is apparent that the flash smelting furnace and the operating method according to this invention are excellent over the flash smelting furnace and the operating method using the conventional concentrate burner. However, according to the study made subsequently, it has been apparent that if the ratio of the silicate ore added other than the sulfide concentrate as the smelting raw material is increased in the operation o~ t~e example, although the ~ate o~ dust gener~tion did not change so much but the ox~en ef~iciency was reduced. This ls assumed to be ~ttributable to the ~ollowing rea~on~.
In accordance wl~h this ope~ting method, since a portion of the reactlon gas is blow~ from an a~r supply nozzle and h~ agains~ a ~et stream ~ormed by the concen-t~ate burner, to form a turbulent flow spreading over the entire re~ion in the re~ct~on sha~t, the smelting raw material blown to~e~her with the auxi~iar~ fuel and the reactlo~ air ~ro~ the conce~trate bu~er into the reaction s~aft is uniformly dispersed 1~ the reactio~ air. In this case, silicate ore, powdery iron concentrat~, copper slag, dust or ~e like, othe~ ~an the sulfide concen~rate added as ~he smelting raw materlal are ~on-combustible sub-stances, whi~h hinder the combustion of the concentrate ore in the reactlon sha~t. Amo~ all. since the silicate ore ~s the main ~ngredient SlO2 the melting point oP
which ls as high as 1720'C. it f5 apparent t~at the com-bustibility of the concent~ate ore is greatly hindered.
ln this operatimg method, since the concentrate ore under com~ustion and silicious sa~d are unifo~mly dispersed in the reaction sh~ft as the ra~o of ~he silicate ore added is inc~eased, th~ silicate ore ~ts as if it were a pow-de~y fire exti~guishing a~e~. This results ln the lowé~-2039~87 ing of the temperature of the concentrate particles under combustion,which suppresses the oxidizing reaction of the concentrate ore itself to reduce the oxygen efficiency.
OBJECT OF THE INVENTION
In view for the foregoing problems, it is an object of the present invention to provide an operating method for a flash smelting furnace capable of remarkably improving the oxygen efficiency and reducing the rate of dust gene-ration in a flash smelting furnace for non-iron metals using an oxygen-enriched air as a reaction air.
SU~IARY OF THE INVENTION
According to the invention there is provided a method of operating a flash smelting furnace having a reaction shaft, a settler having first and second opposite ends connected at said first end to a lower portion of the reaction shaft, said settler having a slag discharge port and a matte discharge port disposed on a side of the settler, an uptake connected to said second end of said settler, and at least one concentrate burner disposed at a top of said reaction shaft or a ceiling of said settler, wherein said concentrate burner comprises at least a concentrate chute, an oxygen blowing tube inserted in said concentrate `- 2û39687 chute, and an ~llxili~ry fuel burner inserted into said oxygen blowing tube, and wherein a lower end of the oxygen blowing tube protrudes downwards to a point below a lower end of the concentrate chute, which method comprises feeding a smelting raw material through said concentrate chute, supplying auxiliary fuel to said auxiliary fuel burner and providing an amount of oxygen in excess of that required for combustion of the auxiliary fuel by blowing industrial oxygen into the furnace through said oxygen blowing tube.
In another aspect of the present invention, all the amount of oxygen required for the combustion of the smelting raw material and the auxiliary fuel is blown into the furnace as an industrial oxygen by way of the oxygen blowing tube.
In a further aspect of the present invention as described above, the lower end of the ~llxili~ry fuel burner is constituted such that it is at an identical level with that for the lower end of the oxygen blowing tube.
In accordance with the constitution as described above, among the smelting raw materials supplied from the concentrate shoot, self-combustible sulfide concentrates such as copper, nickel, zinc and lead are rapidly heated and ignited by radiation heat from a reactor wall.
, ~
an exhaust gas at high temperature or a flame formed by an auxiliary fuel burner. Since an industrial oxygen in an amount required for the combustion of the auxiliary fuel is blown by way of the oxygen blowing tube, the ignited sulfide concentrate is rapidly brought into reaction with the industrial oxygen supplied from the oxygen blowing tube to form a matte and a slag, in which the matte and the slag at high temperature collide against each other to increase the size of particles during falling in the reaction shaft, as well as they also collide against and melt non-combustible substances such as silicate ore, copper slag, powdery iron concentrate and dust added as the smelting raw material. Further, a portion of the non-combustible substances is melted also by the radiation heat due to the combustion of the sulfide concentrate or an exhaust gas at high temperature. In this case, since the industrial oxygen supplied from the oxygen blowing tube means such an oxygen usually at 90% or higher oxygen concentration, the oxidizing reaction (combustion) of the sulfide concentrate is more rapid as compared with the oxidizing reaction with air or oxygen-enriched air. Since air or oxygen-enriched air contains a lot of inert nitro-gen other than oxygen, this hinders the reaction between the sulfide concentrate and oxygen. ~urther, in the case of using the industrial oxygen, the temperature of the exhaust gas mainly composed of S02 released upon combus-tion of the sulfide concentrate is higher than the temper-ature of an exhaust gas in a case of using oxygen or oxygen-enriched air, since there is no requirement for elevating the temperature of nitrogen or the like.- with the functions as described above, since the smelting raw material supplied in the reaction shaft causes efficient reaction with the industrial oxygen, flash smelting at a low rate of dust generation and at high oxygen efficiency is possible.
In particular, if the entire amount of oxygen required for the combustion of the smelting raw material and the auxiliary fuel is blown as an industrial oxygen by way of the oxygen blowing tube into the furnace, it is possible to reduce the rate of dust generation and increase the oxygen efficiency even if the addition ratio of the non combustible substances other than the sulfide concentrate as the smelting raw material is increased, with the reasons described above.
Further, if the lower end of the auxiliary fuel burner is constituted so as to be in the same level as that for the lower end of the oxygen blowing tube, the best result is obtained. This is attributable to that a vigorous heavy oil combustion flame is formed near the lower end and the reaction of the smelting raw material ~, passing through the flame is completed within an extremely short period of time, thereby enabling to extend a time for increasing the size of particles by the collision between each other in the reaction shaft.
DESCRIPTION OF THE ACCOMPANYING DRAWINGS
These and other objects, as well as advantageous features of the present invention will become apparent by reading the following descriptions for preferred embodi-ments with reference to the accompanying drawings, wherein Fig. 1 is a schematic view for a concentrate burner of a flash smelting furnace used in Example 1;
Fig. 2 is a schematic view for a concentrate burner of a flash smelting furnace used in Examples 2 and 3;
and Fig. 3 is a view illustrating a constitution of a conventional flash smelting furnace.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
- The present invention will now be described more in details with reference to examples illustrated in the drawings.
Example 1 Fig. 1 is a schematic view for a concentrate burner .
2' of a flash smelting furnace used in this example, in which a wind box 17 has a restricted portion 17a and an opening 17b diverged downwardly, a concentrate shoot 18 is suspended in the central portion of the window box 17 such that the lower end is situated slightly below the re-stricted portion 17a, an oxygen blowing tube 19 concentri-cally penetrates the concentrate shoot 18 and has a dis-persion cone 20 around the outer periphery at the lower end thereof that protrudes downward to lower than the top end of the concentrate shoot 18, and an auxiliary fuel burner 21 concentrically penetrates the oxygen blowing tube 19 with the lower end thereof being situated at the same level as that for the lower end of the oxygen blowing tube 19. Test operation was conducted by using a medium scale test furnace with a concentrate processing capacity of about 0.8 t/h and having a reaction shaft 3 equipped with such a concentrate burner 2' at the top and having 1.5 m inner diameter and 4.0 m height and a settler 6 having 1.5 m inner diameter and 5.~5 m length (refer to Fig. 3) for four days under the conditions shown in Table 1 below respectively.
.
Table 1 Conditions for Test Operation No.1 No.2 No.3 No.4 Amount of concentrate treated t/h 0.8 0.8 0.8 0.8 Amount of silicate ore treated t/h 0.07 0.07 0.07 0.08 Amount of heavy oill/h 23 23 23 23 Amount of Air Nm3/h 425 425 425 425 Amount of industrial oxygen (90%) Nm3/h 134 134 134 134 Amount of oxygen from oxygen blowing tube (90%) Nm3/h 0 54 134 134 In Table 1, the amount of industrial oxygen means the amount of industrial oxygen used as enriching oxygen, and the amount of oxygen from the oxygen blowing tube means such an amount of oxygen, among the industrial oxygen, that was blown from the oxygen blowing tube 19 into the furnace. In the test operation No. 1 (Comparative Example 1), industrial oxygen and air were mixed and, the entire amount was supplied from the wind box 17. In the test operation No. 2, oxygen in an amount only required for the combustion of heavy oil as an auxiliary fuel (54 Nm3/h) was blown from the oxygen blowing tube 19 into the furnace, while the remaining oxygen was mixed with air and supplied from the window box 17 into the furnace. In the test 20~9B87 operation No. 3, the entire amount of the industrial oxygen (134 Nm3/h) was blown from the oxygen blowing tube 19 into the furnace. In thé'se cases~.(No.l --No.3),~
the lower end of the auxiliary fuel burner 21 was adjusted such that it protruded downwardly to lower than the top end of the oxygen blowing tube 19. Further, in the test operation No. 4, the operati~g conditions were the same as those in the case of the test operation No. 3 excepting that the lower end of the auxiliary fuel burner 21 was situated so as to be at the same level as the lower end of the oxygen blowing tube 19.
The results for each of the test operations No. 1 -No. 4 are be shown in the following Table 2.
Table 2 Result No.l No.2 No.3 No.4 Matte grade -- % 56.8 55.4 69.7 68.9 Temperature of slag C 1226 1235 1277 1289 Rate of dust generation % 15.6 11.3 14.3 10.8 Oxygen efficiency % 82.0 84.5 95.1 98.4 As apparent from the results shown in Table 2, the rate of dust generation is reduced and the oxygen effi-ciency is improved by blowing oxygen in an amount more .
' 20396s7 than that for the auxiliary fuel through the oxygen blow-ing tube 19. That is, ignition and combustion of the auxiliary fuel is usually conducted prior to ignition and combustion of the fine concentrate and, when the amount of industrial oxygen blown from the oxygen blowing tube 19 is increased at least greater than the amount of oxygen required for the combustion of the auxiliary fuel, the concentrate and oxygen cause a vigorous reaction in the high oxygen concentration portion in the thus resultant gas stream, by which the reaction time as a whole can be shortened remarkably.
Particularly, in a case of the test operation No. 4, best operating result can be obtained by not only blowing the entire amount of the enriching oxygen (134 Nm3/h) from the oxygen blowing tube 19 into the furnace but also situating the lower ends for the oxygen blowing tube 19 and the auxiliary fuel burner 21 at an identical level.
with the reasons described below. Since a vigorous com-bustion flame of heavy oil is formed near the top ends of the oxygen blowing tube 19 and the auxiliary fuel burner 21, and the smelting raw material passing in the flame is instantly heated to complete the reaction of the smelting raw material within an extremely short period of time and, as a result, the time for increasing the grain size of particles due to their collision to each other in the reaction shaft 3 can be extended.
Further, the following Tables 3 and 4 show the operati~ conditions and the operating results for the test operation No. 5, in which the lower ends of the oxygen blowing tube 19 and the auxiliary fuel burner 21 were adjusted to an identical level, and only the industrial oxygen was used as the reaction air and the entire amount was blown from the oxygen blowing tube 19 into the furnace in the medium-scaled test furnace described above.
Table 3 20~9687 Conditions for Test Operation No.5 Amount of concentrate treated t/h 0.8 Amount of silicate ore treated t/h 0.07 Amount of heavy oill/h 8 Amount of Air Nm3/h 0 Amount of industrial oxygen (90%) Nm3/h 198 Amount of oxygen from oxygen blowing tube (90%) Nm3/h 198 Table 4 Result No.5 Matte grade~ % 63.3 Temperature of slag C 1299 Rate of dust generation % 4.8 Oxygen efficiency % 100 According to the test operation No. 5, it was possible to remarkably reduce the rate of dust generation and, in particular, increase the oxygen utilization efficiency to 100%.
In this embodiment, the oxygen efficiency can be 2~39~87 improved, in which the dispersion co 20 in the flash smelting furnace uniformly disperses the smelting raw material to prevent the occurrence of a so-called heap (lump of unmelted product).
In a case of using the same conditions as those for the test operation No. 5 and blowing oxygen from the concentrate shoot 18 instead of the oxygen blowing tube 19 into the furnace, the concentrate was burnt at the inside of the concentrate shoot 18 to clog the concentrate shoot 18 within about 2 hours after the start of the test opera-tion.
Example 2 Fig. 2 is a schematic view for a concentrate burner 2" of a flash smelting furnace used in this example 2 consti-tuted by removing the wind box 17 from the concentrate burner of Example 1 (Fig. 1). Then, operation was con-ducted under the conditions shown in the following Table 1 by using asmall-sized experimental flash smelting furnace comprising a reaction shaft 3 having such a concentrate burner 2" disposed at the top and having an inner diameter of 1.5 m and a height of 2.5 m from the ceiling to the melted surface of the settler and a settler 6 having an inner diameter of 1.5 m and a length of 5.25 m, with the amount of the concentrate treated of about 0.8 t/h and the 2~39~87 aimed matte grade - as 50%. In the test operation No.
1, a flame was formed by supplying heavy oil at a rate of 7 l/h from the auxiliary fuel burner. In the test opera-tion No. 2, the heavy oil was not supplied. The opera-tions were conducted for three days and two days respec-tively.
Table l Test Operation No. 1 No. 2 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.868 0.797 Amount of silicate ore treated t/h 0.067 0.057 Amount of heavy oil l/h 7.0 0 Amount of Air supplied Nm3/h 0 0 Amount of industrial oxygen (90% 2) Nm3/h 144.1 139.9 The results are shown in the following Table 2.
Table 2 2039~87 Result No.1 No. 2 Matte grade ~ % 48.4 53.0 Temperature of slag C 1276 1304 Rate of dust generation % 4.3 6.7 Oxygen efficiency % 99.5 98.2 Comparative Example 2 Operation was conducted for two days under the condi-tion No. 3 shown in the Table 3 by using the same small-scaled experimental flash smelting furnace as that in Example 2 having a conventional concentrate burner disposed at the top, with the aimed matte grade as 50%. Further, operation was conducted for three days under the condition No. 4 shown in the following Table 3, with the aimed matte grade as 55 %, by using the same small-sized experimental flash smelting furnace as that in Example 2 having a concentrate burner disposed at the top and a set of air supply nozzles disposed near the central portion for the side wall thereof shown in Japanese Patent Laid-Open Hei 2-230234. In the following Table 3, L represents the height for the reaction shaft and I represents a distance from the ceiling of the reaction shaft to the air supply nozzle.
Table 3 2~9~87 Test Operation No. 3 No. 4 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.772 0.767 Amount of silicate ore treated t/h 0.07 0.081 Amount of heavy oil l/h 12.3 7.1 Amount of Air supplied Nm3/h 455.4 o Amount of industrial oxygen (90% 2) Nm3/h 104-.8 90.4 Air supply nozzle condition:
Amount o~ air supplied Nm3/h - 446.0 Blowing rate m/sec - 49.3 I/L - 0.323 Number of air supply nozzle - 2 Blowing angle - horizontal The results are shown in the following Table 4.
Table 4 Result No.3 No. 4 Matte grade % 53.8 54.2 Temperature of slag C 1315 1274 Rate of dust generation % 10.0 5.3 Oxygen efficiency % 78.3 95.3 As apparent from the comparison for the results 2 0 3 9 ~ 8 7 between Example 2 and Comparative Example 2, it can be seen that the operation method according to the present invention enables an operatin~ with lower rate of dust generation and higher oxygen efficiency than those in the conventional flash smelting furnace.
Example 3 An operation was conducted under the operating condi-tions as shown in the following Table 1 by using the same small-sized experimental flash smelting furnace as in Example 2, with the aimed -matte grade being 50%. In the test operation No. 1, the addition rate of silicate ore to the concentrate was increased and,in thé test operation No. 2,siliciou~ sand and powdery iron concen-trate were added to increase the addition rate of the non-combustible substances, in which operations were conducted for two days and three days respectively.
2039~87 -Table 1 Test Operation No. 1 No. 2 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.7880.809 Amount of silicate ore treated t/h 0.1170.052 Amount of powdery iron concentrate treated t/h 0 0.077 Amount of heavy oil l/h 7.1 7.0 Amount of Air supplied Nm3/h 0 0 Amount of industrial oxygen (90% 2) Nm3/h 145.7 143.3 The results are shown in the following Table 4.
Table 2 Result No.1 No.2 Matte grade % 52.6 52.5 Temperature of slag C 1254 1290 Rate of dust generation % 5.7 4.7 Oxygen efficiency % 99.2 99.8 2039~87 Comparative Example 3 Operation was conducted by a small-sized experimental smelting furnace having a concentrate burner disposed at the top and a pair of air supply nozzles disposed near the central portion on the side wall thereof under the operatinq conditions shown in the following Table 3 with the aimed mat~e grade - being 55% in the same way as the test operation No. 4 in Comparative Example 2. In the test operation No. 3, the addition ratio of silicate ore to the concentrate was increased and, in the test operation No.
4, the silicate ore and the powdery iron concentrate were added to increase the addition ratio of the non-combusti-ble substances, in which operations were conducted for two days and three days respectively. In the following Table 3, L represents the height of the reaction shaft and I
represents a distance from the ceiling of the reaction shaft to the air supply nozzle.
Table 3 Test Operation No. 3 No. 4 Condition Condition for concentrate burner:
Amount of concentrate treated t/h 0.797 0.730 Amount of silicate ore treated t/h 0.131 0.073 Amount of powdery iron concentrate treated t/h O 0.091 Amount of heavy oil l/h 7.0 7.0 Amount of Air supplied Nm3/h 0 0 Amount of industrial oxygen (90% 2) Nm3/h 99.5 102.0 Condition for air supply nozzle:
Amount of air supplied Nm3/h 504.4 475.8 Blowing rate m/sec 55.7 52.6 I/L 0.323 0.323 Number of air supply nozzle 2 2 Blowing angle horizontal horizontal The results are shown in the following Table 4.
.
Table 4 Result No.3 No. 4 Matte grade % 52.5 53.5 Temperature of slag C 1275 1247 Rate of dust generation % 5.5 5.9 Oxygen efficiency % 85.4 80.6 As apparent from the comparison of the results between Example 3 and Comparative Example 3, it can be seen that the operati~ method according to the present invention can provide a flashing smelting furnace opera-tion at low rate of dust generation and high oxygen effi-ciency even if the addition ratio of the non-combustible substances to the concentrate is increased, which was impossible by the conventional operating method.
When the operation was conducted by using the same small-sized experimental flash melting furnace as in the test operation No. 3 of Comparative Example 2 equipped with a conventional concentrate burner, under the condi-tions for the concentrate burner, with the amount of concentrate treated as 0.823 t/h and the amount of sili-cate ore treated as 0.115 t/h, unmelted matters were deposited on the molten surface under the reaction shaft and operation was possible only for four hours.
As has been described above, the operating method for flash smelting furnace according to the present invention can provide a practically important advantage capable of remarkably increasing the oxygen efficiency and reducing the rate of dust generation in a flash smelting furnace for non-iron metals using an oxygen-enriched air as the reaction air.
Claims (7)
1. A method of operating a flash smelting furnace having a reaction shaft, a settler having first and second opposite ends connected at said first end to a lower portion of the reaction shaft, said settler having a slag discharge port and a matte discharge port disposed on a side of the settler, an uptake connected to said second end of said settler, and at least one concentrate burner disposed at a top of said reaction shaft or a ceiling of said settler, wherein said concentrate burner comprises at least a concentrate chute, an oxygen blowing tube inserted in said concentrate chute, and an auxiliary fuel burner inserted into said oxygen blowing tube, and wherein a lower end of the oxygen blowing tube protrudes downwards to a point below a lower end of the concentrate chute, which method comprises feeding a smelting raw material through said concentrate chute, supplying auxiliary fuel to said auxiliary fuel burner and providing an amount of oxygen in excess of that required for combustion of the auxiliary fuel by blowing industrial oxygen into the furnace through said oxygen blowing tube.
2. A method according to claim 1, wherein an amount of industrial oxygen sufficient for combustion of both said auxiliary fuel and said smelting raw material is blown into the furnace through the oxygen blowing tube.
3. A method according to claim 2, wherein the industrial oxygen has an oxygen concentration higher than 90%.
4. A method according to claim 1, wherein a lower end of the auxiliary fuel burner is positioned at the same vertical horizontal level as the lower end of the oxygen blowing tube.
5. A method according to claim 1, wherein said smelting raw material comprises a sulfide concentrate and a non-combustible material.
6. A method according to claim 5, wherein the sulfide concentrate is selected from the group consisting of self combustible copper, self combustible nickel, self combustible zinc and self combustible lead.
7. A method according to claim 5, wherein said non-combustible material is selected from the group consisting of silicate ore, copper slag, powdery iron concentrate and dust.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12193490 | 1990-05-11 | ||
| JP121934/2 | 1990-05-11 | ||
| JP168845/2 | 1990-06-27 | ||
| JP2168845A JPH0747786B2 (en) | 1990-05-11 | 1990-06-27 | Operation method of flash smelting furnace |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2039687A1 CA2039687A1 (en) | 1991-11-12 |
| CA2039687C true CA2039687C (en) | 1997-03-25 |
Family
ID=26459178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002039687A Expired - Lifetime CA2039687C (en) | 1990-05-11 | 1991-04-03 | Method for operation of flash smelting furnace |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH0747786B2 (en) |
| KR (1) | KR930012179B1 (en) |
| AU (1) | AU635128B2 (en) |
| CA (1) | CA2039687C (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5281252A (en) * | 1992-12-18 | 1994-01-25 | Inco Limited | Conversion of non-ferrous sulfides |
| JP3852388B2 (en) * | 2001-09-13 | 2006-11-29 | 住友金属鉱山株式会社 | Concentrate burner for flash smelting furnace |
| FI118540B (en) * | 2006-04-04 | 2007-12-14 | Outotec Oyj | Method and apparatus for treating process gas |
| JP5502047B2 (en) * | 2011-09-30 | 2014-05-28 | パンパシフィック・カッパー株式会社 | How to operate a copper smelting flash furnace |
| CN112981133B (en) * | 2021-02-06 | 2023-01-03 | 易门铜业有限公司 | Method for reducing smoke dust rate of copper smelting bottom blowing furnace |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6256538A (en) * | 1985-09-05 | 1987-03-12 | Sumitomo Metal Mining Co Ltd | Self fluxing smelting furnace |
| JPS63199829A (en) * | 1987-02-13 | 1988-08-18 | Sumitomo Metal Mining Co Ltd | Method for operating flash-smelting furnace |
-
1990
- 1990-06-27 JP JP2168845A patent/JPH0747786B2/en not_active Expired - Fee Related
-
1991
- 1991-04-03 CA CA002039687A patent/CA2039687C/en not_active Expired - Lifetime
- 1991-04-23 AU AU75337/91A patent/AU635128B2/en not_active Expired
- 1991-05-10 KR KR1019910007546A patent/KR930012179B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR910020185A (en) | 1991-12-19 |
| JPH0747786B2 (en) | 1995-05-24 |
| AU7533791A (en) | 1991-11-14 |
| CA2039687A1 (en) | 1991-11-12 |
| JPH0472024A (en) | 1992-03-06 |
| KR930012179B1 (en) | 1993-12-24 |
| AU635128B2 (en) | 1993-03-11 |
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