A method of processing red mud

 

(57) Abstract:

The invention relates to integrated processing of bauxite and can be used to extract valuable components from red mud from alumina production. A method of processing red mud from alumina production involves leaching with sulphuric acid translation of valuable components in the solution, the leaching is carried out with sulfuric acid with a concentration of 74 - 100 g/l at a temperature of not lower than 64oWith, reach a high enough simultaneous extraction from sludge scandium and yttrium, significantly reduces the amount of iron circulating in enriched valuable components of the solution, which facilitates the further processing. Obtained after separation of the solution residue, rich in iron, can be used in the metallurgical industry. In addition, in the method completely exclude using-low-tech hydrochloric acid, and use technology in an industrial environment sulfuric acid of low concentration (less than 10%). table 1.

The invention relates to integrated processing of bauxite, namely the recovery of valuable components from red mud from alumina production.

oC from red mud. The method includes sulfatization belitovogo slurry at 200oC for 1 h, concentrated sulfuric acid, taken to excess, equal to 1.1 to 1.2 with respect to the calculated stoichiometry, extraction at 50oC for 40 min at W:T=10 with a receiving solution in which the concentration of sulfuric acid is 2.4 N. this is achieved by extracting scandium from the slurry by 90%.

The disadvantages of this method are primarily related to the complexity and duration of the technological process of processing of red mud per se, because the red sludge is subjected to annealing at high temperatures, followed by salt extraction, only after which are sulfatization concentrated sulfuric acid to extract valuable component scandium.

The method for extracting scandium from the red mud of alumina production (Patent RF N 2040587, Ál. C 22 B 59/00, 1995), which includes the processing of red mud 3-5% Isatou when 100-1110oC and T:W=1:6-8. The percentage of extraction of scandium is 90-91%.

The known method has a number of disadvantages. This is primarily a two-stage opening of the sludge, while the second stage is carried out with sulfuric acid of high concentration, which is 50-55% or 706-794 g/L. in Addition, in the first stage use-low-tech hydrochloric acid.

It should be noted that waste red mud as a valuable component along with contains scandium and yttrium, the extraction of which has great economic value.

Thus, the authors faced the task of developing a method of processing red mud, which provides simultaneous extraction of scandium and yttrium, preferably the exception of the use of hydrochloric acid and reduce at least some related items transferred into the solution together with scandium and yttrium.

The problem is solved in the method of processing red mud from alumina production by leaching with sulphuric acid translation of valuable components in the solution in which the leaching is carried out with sulfuric acid with a concentration of 74 - 100 g/l at a temperature of not lower than 64oC.

oC with simultaneous extraction of scandium and yttrium.

The proposed method can be implemented as follows. Waste red mud containing oxides of iron, aluminium, calcium, sodium, titanium, scandium, yttrium, leached in sulphuric acid with a concentration of 74 - 100 g/l for 1.5 - 2 hours under stirring at a temperature not lower than 64oC. thereafter, the slurry is filtered or defend for 1 - 1.5 hours and decanted. The total extraction of scandium and yttrium in solution is 30.2 - 86,9% and 75 -100%, respectively. Next, from the obtained solution of scandium and yttrium can be extracted by known methods. The percentage of trace elements in solution is at a level that does not impede subsequent processing solution to obtain scandium and yttrium.

A fairly high percentage of extraction of scandium and yttrium in solution with a slight transition in his accompanying elements is only possible when carrying out the process claimed in the range of parameter values, when you exit a claimed within the specified result is not achieved. At low values of temperature and initial concentration of sulfuric acid has a very low percentage of extraction in a solution of securities psovaya pulp, pulp turns into a thick, sticky "dough" (PL., example 3), which complicates the process in an industrial environment. A further increase in the initial concentration of sulfuric acid above the stated limit while increasing the temperature of the process also causes sagupaan pulp (table. , example 7) or leads to the fact that a large number of related items goes into solution (PL., example 8 and 9).

The proposed method is illustrated by the following examples.

Example 1. 30 g of dry waste sludge containing, by weight. %: Fe2O3is 44.7; Al2O3- 15,0; CaO To 11.2; Na2O - 3,4; SiO2- 7,2; SO3- 5,7; TiO2- 4,28; Y - 0,03; Sc -0,009; the rest is up to 100, handle 136 ml of sulfuric acid solution with a concentration of 74 g/l for 2 h at a temperature of 94oC and stirring with a stirrer. The resulting slurry filtered. Get the solution that passes (% of original): Fe2O3- 1,4; Al2O3- 45,6; Y - 75; Sc - 50.

Other examples of specific performance of the proposed method are shown in table (examples 4-6).

Thus, the proposed method can achieve high enough simultaneous extraction of grinding the components of the solution, to facilitate further processing. Obtained after separation of the solution residue, rich in iron, can be used in the metallurgical industry. In addition, the proposed method completely exclude using-low-tech hydrochloric acid, and use technology in an industrial environment sulfuric acid of low concentration (less than 10%).

A method of processing red mud from alumina production by leaching with sulphuric acid translation of valuable components in solution, characterized in that the leaching of lead in sulphuric acid with a concentration of 74 - 100 g/l at a temperature of not lower than 64oC.

 

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FIELD: metallurgy; reworking wastes of alumina production process.

SUBSTANCE: proposed method includes preparation of batch of charge containing red mud and carbon reductant, heating the charge in melting unit to solid-phase iron reduction temperature, three-phase reduction of ferric oxides in charge by carbon reductant and saturation of iron with carbon in charge thus prepared, melting the reduced charge for obtaining metal phase in form of cast iron and slag phase in form of primary slag, separation of cast iron from primary slag in melt heated to temperature of 40 C, reduction of silicon and titanium from oxides contained in primary slag by aluminum and removal of cast iron and primary slag from melting unit; during preparation of charge, concentrate of titanomagnetite ore containing titanium oxide in the amount from 1 to 15% is added to red mud; besides that, additional amount of carbon reductant and additives are introduced; after separation of primary slag from cast iron in melting unit, cast iron is heated to 1500-1550 C and product containing ferric oxide is added to it; iron is reduced by carbon of cast iron for converting the cast iron into steel at obtaining secondary slag; main portion of steel is removed from melting unit, secondary slag is added to primary slag and silicon and titanium are converted into steel residue in melting unit by reduction with aluminum, thus obtaining final slag-saturated slag and master alloy containing iron, titanium and silicon; main portion of master alloy is removed from melting unit; after removal of final slag for converting the master alloy residue to steel in melting unit, titanium and silicon are converted into slag phase by oxidation and next portion of charge is fed to slag phase formed after converting the master alloy residue to steel. Proposed method ensures high efficiency due to obtaining iron-titanium silicon master alloy in form of independent product and production of alumina from high-alumina final slag or high-alumina cement and concentrate of rare-earth metals.

EFFECT: enhanced efficiency due to avoidance of intermediate remelting of steel.

10 cl, 2 dwg

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