A kind of technology for producing active magnesium oxide
Technical field
The invention belongs to the chemical technique field of energy-saving technology.Relating to contain the magnesium nonmetalliferous ore is raw material, adopts carborization to produce in the activated magnesia process, and Lowlevel thermal energy is recycled, and reduces a kind of technology for producing active magnesium oxide of energy expenditure.
Background technology
Activated magnesia is used for the filler of tamanori, sealing material, plastics, paint and paper etc. mainly as the promotor of chloroprene rubber, viton; Pharmaceutically be used as antacid and laxative, be used for hyperchlorhydria and duodenal ulcer disease; The raw material that also can be used as pottery, glass, senior lagging material agent magnesia cement etc.Activated magnesia is of many uses, and the market requirement increases day by day.
At present production active oxidation magnesium raw material mainly contains rhombspar, magnesite, brucite, hydromagnesite stone, serpentine etc. and contains the magnesium nonmetalliferous ore, and bittern, bischofite, sal epsom etc. contain magnesium soluble inorganic salt class.The former adopts carborization separating calcium and magnesium and other impurity, at first generates Magnesium Carbonate Light 41-45, produces activated magnesia through calcining again, its lighter in weight, active high, tap density is little, receive praises from customers; The latter at first generates magnesium hydroxide with the reaction of bases such as raw material and ammonia, caustic soda, milk of lime, produces activated magnesia through calcining again, and its product is low than the former activity, quality heavy, tap density is big, some user, and particularly high-grade user can't use.
With the rhombspar is raw material, and the operational path that adopts carborization to produce activated magnesia is: rhombspar (MgCO
3CaCO
3) send in the lime calcining kiln by certain proportioning and calcine with anthracite, can obtain dolomite ash (MgOCaO), also claim clinker dolomite.Dolomite ash is sent into digestive shelf and under agitation is digested to the dolomite ash breast with hot water.Dolomite ash breast through refining, transfer dense, temperature adjustment after with being pumped to carbonating tower, the carbonic acid gas kiln gas that feeding derives from the dolomite calcination kiln carries out carburizing reagent to the dolomite ash breast.The main component of the carbonization solution after the carburizing reagent is the Magnesium hydrogen carbonate aqueous solution (also being called heavy magnesium water), and throw out is for containing magnesium lime carbonate.Separate after filtration and obtain the Magnesium hydrogen carbonate clear liquid and contain the magnesium calcium carbonate filter cake.Filter cake drying, classification, pack to such an extent that contain the magnesium calcium carbonate product.Clear liquid makes its pyrolysis generate Magnesium Carbonate Light 41-45 with being pumped into the pyrolysis groove with the steam direct heating.The milk-white coloured suspension that contains Magnesium Carbonate Light 41-45 that generates after the pyrolysis after separating after filtration, carries out drying with the filter cake wet feed, gets the Magnesium Carbonate Light 41-45 product.Magnesium Carbonate Light 41-45 delivered in the calcining furnace further calcine, classified again after finishing, the packing of calcining promptly gets the active oxidation magnesium products.The reaction of whole process is as follows:
Calcining MgCO
3CaCO
3→ MgOCaO+2CO
2↑ (1)
Digestion MgOCaO+2H
2O → Mg (OH)
2+ Ca (OH)
2(2)
Carbonization Ca (OH)
2+ CO
2→ CaCO
3↓+H
2O (3)
Mg(OH)
2+2CO
2→Mg(HCO
3)
2 (4)
Pyrolysis 5Mg (HCO
3)
2→ 4MgCO
3Mg (OH)
24H
2O+6CO
2↑ (5)
Calcining 4MgCO
3Mg (OH)
24H
2O → 5MgO+4CO
2↑+5H
2O (6)
The heavy magnesium water pyrolytic process is lower because of Magnesium hydrogen carbonate solubleness in the above-mentioned production technique, and containing Magnesium hydrogen carbonate concentration in the heavy magnesium water, very little (amount to content of magnesia 6~12g/L), it be 50~90m that 1 ton of Magnesium Carbonate Light 41-45 of every production needs pyrolysis heavy magnesium water amount
3Because this reaction is for thermo-negative reaction, and pyrolysis temperature is 95~105 ℃, near boiling point, a large amount of water evaporations arranged, and need expend a large amount of heat energy.According to pertinent data, the pyrolysis energy consumption accounts for more than 50% of Magnesium Carbonate Light 41-45 production process total energy consumption.In addition, the Magnesium Carbonate Light 41-45 filter cake moisture content that obtains after heavy magnesium water pyrolysis, the filtering separation is higher, is generally about 75%, it is 1 ton of Magnesium Carbonate Light 41-45 of every production, need drying to remove about 3 tons of water, the vaporize water component is very big, causes the energy consumption of Magnesium Carbonate Light 41-45 drying process also very high.
Theoretical analysis and production practice show, the energy consumption of dry these two operations of heavy magnesium water pyrolysis and Magnesium Carbonate Light 41-45 accounts for 70%~80% of whole process energy consumption in the whole process of production of activated magnesia, therefore these two operations are studied, optimize its processing condition, energy-saving and cost-reducing significant to whole technology.
Summary of the invention
The present invention provides a kind of energy consumption low technology for producing active magnesium oxide for overcoming problems of the prior art.The present invention further produces the activated magnesia production process to carborization to carry out energy consumption analysis, set up the pre-pyrolysis operation of heavy magnesium water, the Magnesium Carbonate Light 41-45 dried tail gas is used for the pre-pyrolysis of heavy magnesium water, fully reclaim the dried tail gas heat, further reduce the pyrogenic processes energy consumption, reach energy saving purposes.
The present invention is achieved by the following technical solutions:
A kind of technology for producing active magnesium oxide of the present invention, it may further comprise the steps:
1. heavy magnesium water (being magnesium bicarbonate solution) is put into pre-pyrolyzer, its heavy magnesium water is 6~12g/L in magnesium oxide concentration, and temperature is 10~30 ℃.
Described heavy magnesium water can transfer dense, carbonization, filtering separation to obtain through calcining, digestion, refining, temperature adjustment by containing the magnesium non-metallic minerals.
2. the 1. middle heavy magnesium water through pre-pyrolyzer of step is put into pyrolyzer, feeding saturation steam heats, make the heavy magnesium water temperature be elevated to 95~105 ℃, Magnesium hydrogen carbonate in the heavy magnesium water fully is decomposed into Magnesium Carbonate Light 41-45 precipitation and separates out, and gained suspension separates after filtration and obtains moisture 70%~80% Magnesium Carbonate Light 41-45 filter cake.
3. step Magnesium Carbonate Light 41-45 filter cake is 2. sent into moisture eliminator and carry out drying, obtain the Magnesium Carbonate Light 41-45 product.
4. the tail gas that step drying process is 3. produced is introduced step pre-pyrolyzer 1., dried tail gas is directly fully contacted with heavy magnesium water, carry out heat exchange, reclaim wherein Lowlevel thermal energy and Magnesium Carbonate Light 41-45 dust, and make the heavy magnesium water temperature be elevated to 40~55 ℃ by 10~30 ℃.
5. the 3. dried Magnesium Carbonate Light 41-45 product of step is sent into calcining furnace, calcine 0.5~1h down, promptly get the active oxidation magnesium products at 800 ℃.Can classified again, packing after calcining finishes.
Above-mentioned a kind of technology for producing active magnesium oxide, described step 1. in pre-pyrolyzer be a kind of in bubbling reactor, tower reactor, tubular reactor, spray reactor or the tank reactor.
The heavy magnesium water temperature that above-mentioned a kind of technology for producing active magnesium oxide, described step go out pre-pyrolyzer in 4. is 45~50 ℃.
The 2. middle heavy magnesium water pyrolytic method of above-mentioned a kind of technology for producing active magnesium oxide, described step can also be following steps:
Will be after the pre-pyrolysis of pre-pyrolyzer temperature reach 40~55 ℃ heavy magnesium water and put into pyrolyzer, feeding saturation steam heats, make its temperature be elevated to 50~65 ℃, use vacuum apparatus constantly to vacuumize then, make the inner pounds per square inch absolute (psia) of pyrolyzer remain on 12.33~25.00kPa, time is 20~40 minutes, and the Magnesium hydrogen carbonate in the heavy magnesium water fully is decomposed into Magnesium Carbonate Light 41-45 precipitation and separates out, and gained suspension separates after filtration and obtains moisture 70%~80% Magnesium Carbonate Light 41-45 filter cake.
Above-mentioned a kind of technology for producing active magnesium oxide, the Magnesium Carbonate Light 41-45 dried tail gas temperature of the pre-pyrolyzer of described introducing is 80~150 ℃.
When described a kind of technology for producing active magnesium oxide, the dried dried tail gas of Magnesium Carbonate Light 41-45 are introduced pre-pyrolyzer and reclaimed heat, reclaim the magnesiumcarbonate dust of wherein carrying secretly, reduced environmental pollution, reclaimed intermediates.
In the present invention, the dried tail gas temperature that the Magnesium Carbonate Light 41-45 drying process produces is at 80~150 ℃, the Magnesium Carbonate Light 41-45 dust that wherein contains a large amount of water vapour and carry secretly on a small quantity, in producing at present the Magnesium Carbonate Light 41-45 dried tail gas being carried out emptying handles, not only cause energy dissipation, also environment is on every side polluted simultaneously.The present invention recycles wherein Lowlevel thermal energy and Magnesium Carbonate Light 41-45 dust, be about to dried tail gas and introduce and make the heavy magnesium water temperature be elevated to 40~55 ℃ when pre-pyrolyzer reclaims heat, thereby reduce the energy consumption and the cost of whole production greatly by original 10~30 ℃.The Magnesium Carbonate Light 41-45 dried tail gas is introduced the heavy magnesium water pyrolytic process, reclaim Lowlevel thermal energy wherein, the heavy magnesium water temperature is raise, though like this deficiency so that the Magnesium hydrogen carbonate in the heavy magnesium water fully decompose, but can reduce the saturation steam consumption in the heavy magnesium water pyrolytic process greatly, reduce the primary energy consumption of unit product, reclaim the magnesiumcarbonate dust of carrying secretly in the dried tail gas simultaneously, reduced environmental pollution, killed two birds with one stone.
The present invention has following significant advantage:
Produce activated magnesia technology with traditional carborization and compare, the heat energy consumption of heavy magnesium water pyrolytic process reduces about 60%.The present invention is owing to the recovery of Magnesium Carbonate Light 41-45 dried tail gas low-grade heat, and the pyrogenic processes heat energy consumption reduces more than 20%.The present invention's use that combines with the low temperature pyrogenation technology, activated magnesia ton mark consumption of coal can drop to below the 4t, and compares more than traditional carborization is produced activated magnesia ton mark consumption of coal 8t, and energy-saving effect is obvious.Simultaneously,, reduced the direct environmental pollution caused by discharge of tail gas effectively, and improved product production because the magnesiumcarbonate dust of carrying secretly in the Magnesium Carbonate Light 41-45 dried tail gas is fully reclaimed.Economic benefit and obvious environment benefit.
Embodiment
Below the present invention is described in further detail.
Embodiment one
Pre-pyrolyzer adopts tower reactor, and the reactor useful volume is 15L.Heavy magnesium water flow from carbonation process is 11.8kg/h, and heavy magnesium water is 8.5g/L in magnesium oxide concentration, and temperature is 24.0 ℃, from the spray of pre-pyrolyzer top down; Heavy magnesium water through pre-pyrolyzer is put into pyrolyzer, and heat to wherein feeding saturation steam, make the heavy magnesium water temperature be elevated to 97.5 ℃, Magnesium hydrogen carbonate in the heavy magnesium water fully is decomposed into Magnesium Carbonate Light 41-45 precipitation and separates out, and gained suspension separates after filtration and obtains moisture 76.5% Magnesium Carbonate Light 41-45 filter cake; The Magnesium Carbonate Light 41-45 filter cake is sent into moisture eliminator and is carried out drying, obtains Magnesium Carbonate Light 41-45 product 224.4g/h; Dried Magnesium Carbonate Light 41-45 product is sent into calcining furnace, calcines 1h down at 800 ℃, promptly gets active oxidation magnesium products 93.4g/h; The temperature that drying process is produced is that 92.5 ℃ tail gas draws back pre-pyrolyzer, and dried tail gas is directly fully contacted with heavy magnesium water, carries out heat exchange, recovery Lowlevel thermal energy and Magnesium Carbonate Light 41-45 dust wherein, and make the heavy magnesium water temperature be elevated to 53.4 ℃ by 24.0 ℃.As calculated, this process per hour reclaims the about 1450kJ of heat from dried tail gas, is equivalent to save steam 0.58t/h.
Embodiment two
Adopt bubbling reactor as pre-pyrolyzer, carry out the periodical operation experiment.The bubbling reactor useful volume is 10L, and aspect ratio is 5: 1.Get the 10.0L heavy magnesium water and place bubbling reactor, heavy magnesium water is 7.9g/L in magnesium oxide concentration, and temperature is 18.9 ℃.Feeding saturation steam in bubbling reactor heats, make its temperature be elevated to 62.8 ℃, use vacuum apparatus constantly to vacuumize then, make the inner pounds per square inch absolute (psia) of bubbling reactor remain on 21.00kPa, time is 20~40 minutes, Magnesium hydrogen carbonate in the heavy magnesium water fully is decomposed into Magnesium Carbonate Light 41-45 precipitation and separates out, and gained suspension separates after filtration and obtains moisture 77.8% Magnesium Carbonate Light 41-45 filter cake; The Magnesium Carbonate Light 41-45 filter cake is sent into moisture eliminator and is carried out drying, obtains Magnesium Carbonate Light 41-45 product 170.0g; Dried Magnesium Carbonate Light 41-45 product is sent into calcining furnace, calcines 0.5h down at 800 ℃, promptly gets active oxidation magnesium products 73.6g; Again get the 10.0L heavy magnesium water and place bubbling reactor, heavy magnesium water concentration is 7.9g/L (in content of magnesia), temperature is 19.3 ℃, the temperature that last consignment of Magnesium Carbonate Light 41-45 drying process is produced is that 148.7 ℃ tail gas draws back bubbling reactor, dried tail gas is directly fully contacted with heavy magnesium water, carry out heat exchange, reclaim wherein Lowlevel thermal energy and Magnesium Carbonate Light 41-45 dust, and make the heavy magnesium water temperature be elevated to 44.8 ℃ by 19.3 ℃.As calculated, this process reclaims heat 1070kJ from dried tail gas, is equivalent to save steam 0.43t.