CN103276294B - Method for rapidly reducing nickel slag to produce iron-nickel-copper alloy powder in kiln under reducing atmosphere - Google Patents

Abstract

A method for rapidly and deeply reducing nickel waste slag in a reducing atmosphere kiln to produce iron-nickel-copper alloy powder, which is characterized in that the nickel waste slag, reducing agent and additives are mixed and crushed or ground to a 200-mesh sieve of 20%~ 40%, mixed with binder and water accounting for 5-20% of the dry mass of the whole material, after mixing evenly, use a ball pressing machine or a section machine to make small balls with a diameter of 15mm-30mm or a diameter and a height of 15mm-30mm The small cylinders are laid flat on the bottom of the kiln after drying. The thickness of the material layer is 20mm-45mm. The reduction temperature of the material layer is 1250°C-1450°C, and the reduction time is 10-40min. After cooling, crushing, wet grinding and wet magnetic separation of the reduced material ball or material section, the iron-nickel-copper alloy powder with an iron recovery rate of 85% to 99% is obtained. The iron content in the obtained product is 88% to 98%, and the nickel content is 0.13%~1.98%, copper content 0.14%~1.29%, particle size 3~100um, can be used as raw material for smelting weathering steel. The tailings from wet grinding and wet magnetic separation can be used as raw materials for extracting wollastonite or producing hollow sintered bricks.

Description

A method for rapidly reducing nickel slag in a reducing atmosphere kiln to produce iron-nickel-copper alloy powder

technical background

The invention relates to the field of comprehensive utilization of resources, and provides a method for rapidly reducing nickel waste slag in a reducing atmosphere kiln to produce iron-nickel-copper alloy powder.

my country currently produces about 2 million tons of nickel waste slag annually, and about 4,600 tons of metallic nickel and 3,200 tons of metallic copper are wasted in the national nickel waste slag. In addition to the high value of residual metals such as nickel and copper, nickel waste slag often contains 30% to 50% iron. The iron in nickel waste slag mainly exists in the form of iron silicate, so the traditional beneficiation method is adopted The iron therein cannot be enriched to the grade of marketable iron ore concentrate powder. At present, my country's nickel waste slag is generally sold to cement plants as ingredients for firing cement clinker, and the proportion is generally 3% to 5%. Due to the lack of cement enterprises in the western region, it is impossible to consume a large amount of nickel waste slag. Therefore, the nickel waste slag is basically in the state of stockpiling. The stockpile of nickel slag in the country has reached 40 million tons. If it is converted into metal, about 16 million tons of iron metal, 64,000 tons of copper metal and 92,000 tons of nickel metal have been accumulated and disposed of. The actual cut-off grade of iron ore mining in my country is 10%-30%, and the iron content in nickel waste slag is much higher than the actual cut-off grade of iron ore mining in my country. However, since the iron in the nickel waste slag mainly exists in the form of iron silicate, the traditional beneficiation process cannot effectively enrich the iron in it. Therefore, whether it is sold to a cement plant as an ingredient for burning cement clinker or dumped for disposal, it will cause a huge waste of nickel resources, copper resources and iron resources in this slag.

The purpose of the present invention is to extract the residual nickel, copper and a large amount of iron resources in the form of iron-nickel-copper alloy powder, so that the extracted products have higher value and create economic, environmental and social benefits.

The prior art most closely related to the present invention is the reduction roasting magnetic separation of various refractory iron ores.

The patent with the publication number of CN101161830A describes a reduction roasting process of mineral powder pelletizing, including pelletizing process and roasting process, using unique formula and process, on the premise of producing qualified roasted ore ball products, the mineral powder can be It is used for iron and steel smelting, fully utilizes and saves natural resources, effectively protects the environment and saves production costs of enterprises. This invention only involves the pelletizing process and the roasting process. The average iron grade of the roasted ore balls is 45% to 63%, and such products cannot be directly used for steelmaking. The technique does not provide data on iron reduction rate, iron particle size and selectivity in pellets after roasting.

The patent with the publication number CN101063181A describes a method for quickly reducing carbon-containing gold-containing pyrite pellets to enrich gold and co-produce iron powder by using a rotary hearth furnace. The time is short, the reaction time is fast, the production efficiency is high, the recovery rate of gold and iron is high, the cost is low, and it is easy to control automatically. However, the iron in the material involved in this technology is mainly iron oxide, and no method for controlling the reduction of iron silicate is given. This technology also does not provide an effective method for how to deal with the tail gas of the strongly reducing rotary hearth furnace, and it is difficult to implement it industrially under the situation that the existing country advocates energy conservation and emission reduction. In addition, the three embodiments given in this technology are all about the treatment of magnesia lateritic nickel ore, which are inconsistent with the description in the invention and cannot be implemented.

The patent with the publication number CN101413057A describes a high-efficiency separation method for low-grade and complex iron ores, which classifies and processes complex iron ores of different grades and types, obtains lump ore and ore powder, pelletizes, drys and preheats, reduces and roasts, Cooling, ball milling, magnetic separation, ball milling, magnetic separation or reverse flotation to obtain iron concentrate or reduced iron powder. This patent adopts the chain plate machine-shaft furnace process, and carries out weak reduction at 900℃～1000℃. The raw material used is only low-grade iron ore with iron oxide as the main iron-containing mineral, and does not involve the control of silicic acid. Iron reduction technology. In addition, this technology does not involve the technical problem of reuse of weakly reducing tail gas.

Contents of the invention

The purpose of the present invention is to mainly solve two core technical problems: one is to create a high-temperature and strong reducing atmosphere at 1250°C to 1450°C in the kiln, and at the same time use the physical heat energy and chemical heat energy of the high-temperature and strong reduction tail gas; In the reaction process, under the action of lime, sodium carbonate and other additives, the Fe ²⁺ in the iron silicate is replaced, and more than 99% is reduced to metallic iron, and the metallic nickel and copper are controlled to enter the metallic iron to form iron-nickel-copper alloy powder. The size of the iron-nickel-copper alloy powder is controlled at 3-100um, so that the subsequent wet grinding and wet weak magnetic separation can select the iron-nickel-copper alloy powder with an iron grade and a recovery rate of more than 90%.

The present invention proposes a method for producing iron-nickel-copper alloy micropowder by rapid and deep reduction of nickel waste slag in a reducing atmosphere kiln, which is controlled by the kiln, batching, pelletizing or segmenting, deep reduction roasting and crushing wet grinding-wet grinding It consists of four parts including French magnetic separation.

In order to control the strong reducing atmosphere inside the kiln, the supply of air or oxygen or oxygen-enriched air when the kiln is burning is 40% to 60% of the total air or oxygen or oxygen-enriched air required for the complete combustion of the supplied fuel. The amount of air or oxygen or oxygen-enriched air required for the above-mentioned complete combustion refers to the theoretically calculated amount required to convert 100% of various carbon-containing compounds in the fuel into CO ₂ .

In order to maintain a strong reducing atmosphere in the kiln and achieve the high temperature of 1250 ℃ ~ 1450 ℃ required for rapid and deep reduction in the kiln, high temperature preheating treatment is required for fuel gas and air or oxygen or oxygen-enriched air . The fuel gas used is natural gas or coal bed methane or petroleum gas or shale gas or coal gas. The preheating of the fuel gas uses a tube heat exchanger to exchange heat with the high-temperature waste gas discharged from the deep reduction kiln. The temperature of the preheated fuel gas is 300°C to 500°C. The preheating of air or oxygen or oxygen-enriched air adopts regenerative high-temperature combustion technology or hot blast stove, and the heating of hot blast stove uses strong reducing exhaust gas discharged from deep reduction kiln as fuel. After air or oxygen or oxygen-enriched air is preheated by regenerative high-temperature combustion technology or hot blast stove, the temperature reaches 900°C to 1300°C. In this way, through the above-mentioned double preheating technology of fuel gas and air or oxygen or oxygen-enriched air, the high temperature and strong reducing environment in the deep reduction furnace are realized, and the physical heat energy and chemical heat energy of the strong reduction waste gas are all recycled and used, eliminating emissions Harmful components such as CO and CH ₄ in the exhaust gas have strong pollution to the atmosphere.

The proportion of nickel waste slag, reducing agent, additive and binder used in the batching of the present invention is nickel waste slag:reducing agent:additive:binding agent=100:12-28:5-10:1-5.

The mass percentages of the main chemical components of the nickel waste slag are: TFe: 35%-45%, SiO ₂ : 30%-40%, Al ₂ O ₃ : 2%-7%, MgO: 1%-10%, CaO : 1% to 5%, Ni: 0.1% to 0.8%, Cu: 0.1% to 1.2%, others: 0.1% to 3%. (Note: Total iron TFe refers to all iron in any form, including free iron and iron combined with oxygen or other elements. The total iron content of 35% to 45% is converted to iron oxide content and expressed as 45% to 64%. , and the sum of mass percentages of other components can reach 100%.) The reducing agent is one or a combination of coke powder, lignite, bituminous coal, and anthracite. The additive is one or a combination of limestone, lime, sodium carbonate, fluorite and industrial alkali. The binder is one or a combination of clay, water glass, red mud, sludge and organic binders.

Mix and crush the above-mentioned nickel waste, reducing agent and additives in proportion to 20%-40% of the 200-mesh sieve, add binder and water accounting for 5-20% of the dry mass of all materials, and mix well Use a briquette machine or a section machine to make small balls with a diameter of 15mm to 30mm or small cylinders with a diameter and height of 15mm to 30mm, and spread them on the bottom of the kiln after drying. The thickness of the material layer is 20mm to 45mm. The reduction temperature is 1250°C-1450°C, and the reduction time is 10-40min. In the reduced material ball or section, 99.1% to 99.8% of the various forms of iron in the original material are reduced to metallic iron, and 85.2% to 99.5% of the various forms of nickel in the original material are reduced to metal Nickel, and into the metallic iron particles. 88.3% to 99.5% of the various forms of copper in the original material are reduced to metallic copper and enter metallic iron particles. After deep reduction, the pellets or sections are cooled, crushed, wet-milled, and wet-magnetic-separated to obtain iron-nickel-copper alloy fine powder with an iron recovery rate of 85% to 99%. The iron content in the obtained product is 88% to 98%, and the nickel The content is 0.13%-1.98%, the copper content is 0.14%-1.29%, and the particle size is 3-100um. It can be used as a raw material for smelting weathering steel. The tailings from wet grinding and wet magnetic separation can be used as raw materials for extracting wollastonite or producing hollow sintered bricks.

Beneficial effects of the present invention

1. Extract the iron and residual nickel and copper from a large amount of iron silicate in the nickel waste slag that cannot be selected by the traditional mineral processing technology and the existing reduction roasting magnetic separation technology, and transform it into a high value-added iron-nickel-copper alloy powder ;

2. Compared with other existing reducing kiln reduction and roasting processes, while achieving a high-temperature strong reducing environment, it also realizes the recovery and reuse of the physical heat energy and chemical heat energy of the high-temperature strong reduction waste gas, avoiding the reutilization of waste gas into the atmosphere Emission of highly polluting gases such as CO and CH ₄ improves energy utilization efficiency;

3. Compared with the existing oxidizing atmosphere kiln and kiln furniture sealing deep reduction technology, the reduction time is shortened by more than 10 times, which is conducive to improving efficiency and reducing costs;

4. Realized the simultaneous extraction and utilization of three main valuable metals in nickel waste slag—iron, nickel and copper, which is of great significance to the comprehensive utilization of nickel waste slag;

5. Since most of the metal elements such as iron, nickel and copper have been removed from the tailings of wet grinding and wet magnetic separation, it is conducive to the production of tailings and environmentally friendly hollow sintering.

Description of drawings

Fig. 1 is the process flow diagram of producing iron-nickel-copper alloy micropowder by processing nickel waste slag in reducing atmosphere kiln of the present invention.

detailed description

With reference to Fig. 1, implement the present invention according to process flow diagram of the present invention, comprise:

1. Raw material preparation stage:

The used nickel waste slag, reducing agent (coke powder, lignite, bituminous coal, anthracite, one or a combination of several kinds), additives (limestone, lime, sodium carbonate, fluorite, industrial alkali or one or a certain combination) Combination of several types) crushing and grinding until 20% to 40% of the 200-mesh sieve;

2. Ingredients process:

As can be seen from Figure 1, the test ingredients include four parts: nickel waste slag, reducing agent, additives and binders. In the present invention, the ratio of nickel waste slag, reducing agent, additive and binder is: nickel waste slag: reducing agent: additive: binder=100:12-28:5-10:1-5.

3. Mixing process:

Fully mix the raw materials prepared in step 2 to ensure that the mixed materials are uniform;

4. Ball or column pressure process

Add the mixed material to 5% to 20% of the dry mass of the whole material, and stir evenly at the same time, press it into a 15-30mm pellet with a ball press or use a section machine to make a bottom surface with a diameter and height of 15-20mm. 30mm small cylinder and dry it.

5. Loading and reduction process:

The pressed material balls or material sections are dried and then placed in a reducing atmosphere kiln for deep reduction roasting at a certain reduction temperature. The material layer is evenly spread on the bottom of the furnace, during which it undergoes preheating, heating, and deep reduction. The mixed material is mainly subjected to deep reduction in the deep reduction temperature zone. The reduction temperature is 1250°C-1450°C, and the reduction time is 10-40 minutes. When the temperature drops below 80°C, the material is taken out of the reducing atmosphere kiln. In the reduced material ball or material section, 99% to 99.8% of the various forms of iron in the original material are reduced to metallic iron. 90% to 99.8% of the various forms of nickel in the original material are reduced to metallic nickel and enter metallic iron particles. 90% to 99.8% of the various forms of copper in the original material are reduced to metallic copper and enter metallic iron particles.

6. Crushing, wet grinding and wet magnetic separation process

As shown in Figure 1, after cooling, crushing, wet grinding, and wet magnetic separation of the reduced material ball or material section, iron-nickel-copper alloy micropowder with an iron recovery rate of 85% to 99% can be obtained, and the iron content in the obtained product is 88%. ~98%, the nickel content is 0.13%~1.98%, the copper content is 0.14%~1.29%, the particle size is 3~100um, it can be used as the raw material for smelting weather-resistant steel, and the tailings from wet grinding and wet magnetic separation can be used to extract silica fume Stone or raw material for producing hollow sintered bricks.

Example 1

The process flow of this embodiment consists of four parts: kiln control, batching, section making, deep reduction roasting and crushing wet grinding-wet magnetic separation.

In order to control the strong reducing atmosphere inside the kiln, the air supply during the kiln combustion is 50% of the total air required for the complete combustion of the supplied fuel. The above-mentioned air required for complete combustion refers to the theoretically calculated amount required to convert 100% of various carbon-containing compounds in the fuel into CO ₂ .

In order to maintain a strong reducing atmosphere in the kiln and achieve the high temperature of 1350°C required for rapid and deep reduction in the kiln, both fuel gas and air need to be preheated at high temperature. The fuel gas used is natural gas. The preheating of natural gas adopts the tube heat exchanger to exchange heat with the high-temperature waste gas discharged from the deep reduction kiln. The temperature of the preheated natural gas is 500°C. After preheating by thermal high-temperature combustion technology, the temperature reaches 1200°C. In this way, through the above-mentioned double preheating technology of fuel gas and air, the high temperature and strong reducing environment in the deep reduction furnace are realized, and the physical heat energy and chemical heat energy of the strong reduction waste gas are all recycled, and CO, CH ₄ in the exhaust gas are eliminated. and other harmful components that have strong pollution to the atmosphere.

The proportion of nickel waste slag, reducing agent, additive and binder used in the ingredients of this embodiment is, nickel waste slag: reducing agent: additive: binder = 100:20:5.4:5. The main chemical composition of nickel waste used is: TFe41.31%, SiO ₂ 35.62%, Al ₂ O ₃ 2.43%, MgO8.74%, CaO3.29%, Ni0.22%, Cu0.19%, other 2.9% . The reducing agent used is lignite, the additive used is lime, and the binder used is sodium carboxymethylcellulose (CMC).

Mix and grind the above-mentioned nickel waste slag, lignite and lime in proportion to the remaining 20% of the 200 mesh sieve, add binder and water accounting for 10% of the dry mass of the whole material, and use a section machine to make the diameter and height after mixing. They are all small cylinders of 20mm, and they are laid flat on the bottom of the kiln after drying. The iron-nickel-copper alloy fine powder obtained by wet magnetic separation has an iron recovery rate of 94.65%. The iron content in the obtained product is 91.38%, the nickel content is 0.42%, the copper content is 0.26%, and the particle size is 5-70um. It can be used as a smelting weather-resistant steel raw materials. Wet grinding adopts one-stage grinding, the grinding concentration is 65%, and the grinding time is 20 minutes; the magnetic field strength of wet magnetic separation is 60.8KA/m. The tailings from wet grinding and wet magnetic separation can be used as raw materials for extracting wollastonite or producing hollow sintered bricks.

Example 2

The main chemical composition of the nickel waste used is: TFe40.21%, SiO ₂ 34.61%, Al ₂ O ₃ 2.26%, MgO8.86%, CaO3.37%, Ni0.23%, Cu0.16%, other 2.6% . The reducing agent used is lignite, the additive used is lime, and the binder used is sodium carboxymethylcellulose (CMC). Mix and grind the above nickel waste slag, lignite and lime in proportion to 20% of the remaining 200 mesh sieve, add binder and water accounting for 9% of the dry basis of all materials, and use a section machine to make the diameter and height after mixing. They are all small cylinders of 20mm, and they are laid flat on the bottom of the kiln after drying. The thickness of the material layer is 30mm. The iron-nickel-copper alloy powder with an iron recovery rate of 97.51% was obtained by magnetic separation. The iron content of the obtained product is 91.97%, the nickel content is 0.47%, the copper content is 0.28%, and the particle size is 5-70um. It can be used as a raw material for smelting weathering steel . Wet grinding adopts one-stage grinding, the grinding concentration is 65%, and the grinding time is 20 minutes; the magnetic field strength of wet magnetic separation is 60.8KA/m. The tailings from wet grinding and wet magnetic separation can be used as raw materials for extracting wollastonite or hollow sintered bricks.

Example 3

The proportion of nickel waste slag, reducing agent, additive and binder used in the batching of this embodiment is, nickel waste slag:reducing agent:additive:binding agent=100:14:5.4:5. The main chemical composition of nickel waste used is: TFe42.31%, SiO ₂ 35.60%, Al ₂ O ₃ 2.37%, MgO5.77%, CaO3.26%, Ni0.22%, Cu0.16%, other 2.55% . The reducing agent used is coke powder, the additive used is lime, and the binder used is sodium carboxymethylcellulose (CMC).

Mix and grind the above-mentioned nickel waste slag, coke powder and lime in proportion to the remaining 20% of the 200 mesh sieve, add binder and water accounting for 10% of the dry basis of all materials, and use a section machine to make diameter and Small cylinders with a height of 20mm are laid flat on the bottom of the kiln after drying. The thickness of the material layer is 30mm. The reduction temperature of the material layer is 1350°C and the reduction time is 20min. The reduced material section is cooled, crushed, wet-milled, The iron-nickel-copper alloy powder with an iron recovery rate of 90.61% was obtained by wet magnetic separation. The iron content of the obtained product was 91.74%, the nickel content was 0.45%, the copper content was 0.35%, and the particle size was 6-85um. It can be used as a base for smelting weathering steel raw material. Wet grinding adopts one-stage grinding, the grinding concentration is 65%, and the grinding time is 20 minutes; the magnetic field strength of wet magnetic separation is 60.8KA/m. The tailings from wet grinding and wet magnetic separation can be used as raw materials for extracting wollastonite or producing hollow sintered bricks.

Example 4

The proportion of nickel waste slag, reducing agent, additive and binder used in the ingredients of this embodiment is, nickel waste slag: reducing agent: additive: binder = 100:20:6:5. The main chemical composition of nickel waste used is: TFe40.52%, SiO ₂ 31.64%, Al ₂ O ₃ 3.76%, MgO3.62%, CaO2.73%, Ni0.21%, Cu0.18%, other 2.06% . The reducing agent used is coke powder, the additive used is lime, and the binder used is sodium carboxymethylcellulose (CMC).

The above-mentioned nickel waste slag, coke powder and lime are mixed and ground in proportion to the remaining 20% of the 200 mesh sieve, mixed with binder and water accounting for 8% of the dry mass of the whole material, and after mixing, use a section machine to make diameter and Small cylinders with a height of 20mm are laid flat on the bottom of the kiln after drying. The thickness of the material layer is 30mm. The reduction temperature of the material layer is 1350°C, and the reduction time is 30min. The reduced material section is cooled, crushed, wet-milled, The iron-nickel-copper alloy powder with an iron recovery rate of 92.01% was obtained by wet magnetic separation. The iron content of the obtained product is 92.11%, the nickel content is 0.41%, the copper content is 0.31%, and the particle size is 7-90um. It can be used as a base for smelting weathering steel raw material. Wet grinding adopts one-stage grinding, the grinding concentration is 65%, and the grinding time is 20 minutes; the magnetic field strength of wet magnetic separation is 60.8KA/m. The tailings from wet grinding and wet magnetic separation can be used as raw materials for extracting wollastonite or producing hollow sintered bricks.

Claims (3)

1. A method for producing iron-nickel-copper alloy micropowder by fast and deep reduction of nickel waste slag in a reducing atmosphere kiln, characterized in that: nickel waste slag, reductant and additives are mixed and crushed in proportion or ground to 200 mesh sieves. % to 40%, mixed with binder and water accounting for 5% to 20% of the dry mass of the whole material, the ratio of nickel waste slag, reducing agent, additive and binder is, nickel waste slag: reducing agent: additive: Binder = 100: 12-28: 5-10: 1-5; after mixing evenly, use a briquette machine or a section machine to make small balls with a diameter of 15mm to 30mm or small cylinders with a diameter and height of 15mm to 30mm. After drying, spread it on the bottom of the kiln. The thickness of the material layer is 20mm-45mm. The reduction temperature of the material layer is 1250°C-1450°C, and the reduction time is 10-40min. Wet grinding and wet magnetic separation can obtain iron-nickel-copper alloy powder with an iron recovery rate of 85%-99%. The iron content in the obtained product is 88%-98%, the nickel content is 0.13%-1.98%, and the copper content is 0.14%- 1.29%, with a particle size of 3-100um, it can be used as raw material for smelting weathering steel; tailings from wet grinding and wet magnetic separation can be used as raw material for extracting wollastonite or producing hollow sintered bricks. 2. The method for producing iron-nickel-copper alloy micropowder by fast deep reduction of nickel waste slag in a reducing atmosphere kiln according to claim 1, characterized in that the main chemical composition of said nickel waste slag is: TFe: 35%～ 45%, SiO ₂ : 30%-40%, Al ₂ O ₃ : 2%-7%, MgO: 1%-10%, CaO: 1%-5%, Ni: 0.1%-0.8%, Cu: 0.1 % to 1.2%, others: 0.1% to 3%; the reducing agent is one or a combination of coke powder, lignite, bituminous coal, anthracite; the additive is limestone, lime, sodium carbonate, fluorite , one or some combination of industrial alkalis; the binder is one or some combination of clay, water glass, red mud, sludge and organic binders. 3. the method for the production of iron-nickel-copper alloy micro-powder by rapid deep reduction of nickel waste slag in a kind of reducing atmosphere kiln according to claim 1, is characterized in that, fuel gas used is natural gas or coal bed methane or petroleum gas or shale gas or coal gas; the preheating of fuel gas adopts tubular heat exchanger to exchange heat with the high-temperature exhaust gas discharged from the deep reduction kiln. The temperature of the preheated fuel gas is 300 ℃ ~ 500 ℃. The preheating adopts regenerative high-temperature combustion technology or hot blast stove, and the heating of hot blast stove uses strong reducing exhaust gas discharged from deep reduction kiln as fuel, and air or oxygen or oxygen-enriched air is preheated by regenerative high-temperature combustion technology or hot blast stove After that, the temperature reaches 900℃～1300℃.