A method of processing carbon slurry output from the system the electrolytic production of aluminum
(57) Abstract:The invention relates to ferrous metallurgy, in particular to the production of aluminium and alumina, and may be used in the disposal of carbon sludge being withdrawn from the system the electrolytic production of aluminum. The method is intended for processing carbonaceous slurry (tailings of coal flotation foam, dust and sludge gas purification electrolysis production), containing mainly dispersed particles of carbon, fluorine compounds cryolite, alumina, humidity up to 40% neutralization of fluorides, cyanides, removing oxides of aluminum, alkali metals, useful use of carbon in the process, improve the ecological environment. Carbon slurry output from the system the electrolytic production of aluminum, is administered as a component of the additive in the raw material alumina-soda-isostractural the mixture (slurry) alumina production and the joint is subjected to heat treatment at temperatures above 1000°C in the sintering furnace to obtain the sintered mass - SPECA. In the sintering process is the burning of carbon slurry, the formation of aluminates of sodium (potassium), neutralization of RA is inozemnogo production for the extraction of alumina and alkali metals in the form of alumina, soda, potash, and ensures the improvement of the ecological state of the environment, the extraction of raw materials and the carbonaceous slurry of about 90% of the contained aluminum compounds, alkaline metals. 1 C.p. f-crystals, 2 tab. The invention relates to ferrous metallurgy, in particular to the production of aluminium and alumina, and may be used in the disposal of carbon sludge being withdrawn from the system the electrolytic production of aluminum.Carbon slurry output from the system the electrolytic production of aluminum (tails coal flotation foam, dust and sludge gas purification electrolysis production), containing mainly dispersed carbon particles impregnated with cryolite, alumina, with a humidity of 40% is a waste electrolysis production. The amount of sludge accumulated by enterprises of the Russian aluminum industry on 1.01.99, a total of ~ 2.4 million tonnes and is growing at 150 thousand tons.A method of refining carbonaceous sludge, in particular the flotation tailings coal foam on the author's certificate USSR N 1141083, class C 04 B 33/00, published 85.02.23, which provides for the purpose of reducing the firing temperature of simultaneous ins - 15-20% and the flotation tailings coal foam - aluminum waste production - 8-10%.You know the proposal of Arluke B. I. "Improvement of processing aluminate-alkaline nepheline class", M, 1978, pp. 13, 14, was adopted as a prototype, the introduction as stimulating the process of sintering additives in the mixture for sintering of alumina production, in particular electrostatic dust and sludge gas purification electrolytic cells containing fluorine, carbon, etc. in an amount corresponding in terms of fluorine ~ 0.25% of the mass of the charge.The disadvantage of this proposal is that these substances are considered only as carriers of fluorine and carbon to intensify the sintering process.The technical challenge is to provide comprehensive recycling carbon slurry output from the system the electrolytic production of aluminum using carbon slurry in the process, removing from the slurry of oxides of aluminum, alkali metals, neutralization of soluble fluorides, cyanides; use remaining after the extraction of valuable components and removal (oxidation) of carbon residues in the production of cement, sand-lime brick road stroitelstwom the production process of alumina redistribution sintering.The technical result is achieved by the fact that according to the way carbon slurry with regrinding or without it, in the form of a slurry or partially dehydrated particle size of less than 1 mm, is introduced into the raw material alumina-soda-isostractural the mixture in an amount up to 10% (by dry weight), which is then directed into the furnace sintering (e.g., rotating) the production of alumina. Regrinding carbon slurry possibly in conjunction with the grinding of raw materials (limestone, etc.,) in the preparation of the mixture for sintering.In the above-mentioned mixture with the carbonaceous limestone slurry is injected in an amount to provide binding of fluorine and silicon mixture in the form of cuspidine - CaF23CaO2SiO2, ducellier silicate - 2CaOSiO2, of calcium fluoride, CaF2.The alkali content for the formation of aluminate and ferrite sodium (potassium) adjusting the composition of the mixture before sintering, providing a molecular ratio
< / BR>Carbon slurry, adjusting the composition of the pulp additives limestone and alkali can be introduced into it in any convenient technology place before sintering.When heat-treated in a furnace sintering at temperatures above 1000oC is wsimages the solubility of dicalcium silicate, of calcium fluoride, cuspidine and other binary, ternary compounds.The carbon component of the mixture is burned in the furnace that reduces specific fuel supplied to the furnace sintering in the process.Under high temperatures the decomposition (reduction) of cyanide with the formation of nitrogen, oxides of carbon and nitrogen.Obtained in the furnace sintering the sintered mass - spec - processed by traditional methods in the production of alumina from alumina production, soda derivatives;, codewelcome solution and solids - sludge.Fluoride compounds related in the sintering process in insoluble form, deduce the composition of the sludge, which depending on the composition direct the production of cement, silicate brick (belitovogo sludge), road construction.The ability of the method was tested in laboratory conditions; results are shown in tables 1 and 2.As follows from table 1, the joint processing of carbonaceous slurry of alumina-containing raw material a mixture of alumina production allows you to extract a significant amount of oxides of aluminum is sestertia mixture. From table 2 it follows that the input carbon sludge in the raw material mixture, reduces the specific output of the residue after leaching (sludge) in relation to the weight of the dry mixture, reducing the relative amount of waste residue after leaching.Using the proposed method will allow you to:
to improve the ecological environment in the vicinity of our plants, the aluminum industry by linking harmful soluble forms of fluoride insoluble low-risk forms, neutralization, decomposition of hazardous cyanide in a safe nitrogen and oxides of nitrogen and carbon, the elimination (or substantial reduction) of sludge fields, ensuring practically low-waste technology for the production of aluminium;
- extract from the raw material and the carbonaceous slurry of about 90% of the contained aluminum compounds, alkaline metals;
- to use as fuel and reductant contained in the carbon slurry carbon;
- use solid residue after chemical processing SPECA-sludge in cement production, silicate bricks, road construction;
to improve the economic efficiency of the production of alumina and aluminium.
2CaF23CaO 2SiO2, 2CaO SiO2.2. The method according to p. 1, characterized in that soda (in terms of Na2O) is metered into a mixture of conditions ensuring molecular formula:
FIELD: mining industry.
SUBSTANCE: method comprises washing of bauxite with water simultaneously with grinding, multistep separation of resulting pulp on hydrocyclones, leaching of separated sands in Bayer branch, and separation of sands from effluent and sintering thereof. According to invention, hydrocyclone separation is effected at least in three steps and sintered are sands from the last steps, whereas sands from preceding steps are leached. Drain from the last step is withdrawn from process. Separation of pulp in all but the first stages is effect on a hydrocyclone series wherein diameter of apparatus diminishes in each next step. Number of separation steps is found from summary content of kaolinite and goethite in the last-step drain.
EFFECT: enabled concentration of bauxite due to removal of finest fraction, mainly kaolinite and goethite, reduced losses of aluminum hydroxide and alkali, reduced consumption of flocculant, and reduced loading of sintering furnaces.
3 cl, 4 dwg, 1 tbl