Describe the technology of alumina and secondary products production in the Republic of Kazakhstan

     Alumina is a technical aluminum oxide Al2O3 - a white crystalline powder consisting of α-Al2O3 and γ-Al2O3 modifications. The aluminum production technology consists of two stages: the first is the production of alumina and the second is the electrolytic production of aluminum from alumina. Abroad, almost all Al2O3 is obtained from bauxite mainly by the Bayer method (KI Bayer is an Austrian engineer working in Russia), in domestic plants alumina is obtained from bauxite by the Bayer method and from bauxite and nepheline by sintering. Both of these methods relate to alkaline methods of extracting alumina from ores.1. The essence of the Bayer process consists in leaching a pre-crushed bauxite with an alkaline-aluminate solution and further separation from aluminum hydroxide solution. Aluminum-containing minerals interact with caustic alkali solution (NaOH), as a result of which aluminum goes into solution in the form of sodium aluminate.Al₂O₃·nH₂O_тв + 2NaOH_р-р + (3-n)H₂O_р-р→ 2NaAl(OH)_4р-р ;NaAl(OH)_4р-р ↔ Al(OH)_3тв + NaOH_р-р .(гидроксид алюминия) Al(OH)₃ → Al₂O₃ (глинозём)2. The essence of the method of sintering is to obtain solid aluminates by sintering them at high (~ 1300 ° C) temperatures and in the subsequent leaching of the obtained cake.

Al2O3 + Na2,CO3 = Na2O • Al2O3 + СО,

Na2O • Al2O3 + CO2 + 3Н20 = Al2O3 - 3H2O + Na2CO3

 

4. Name and describe the main methods of processing of raw materials of rare earth metals (REM).
   Processing phosphate rare earth concentrate isolated from apatite, including decomposition of the concentrate with nitric or hydrochloric acid when heated, treating with oxalic acid with precipitation of rare earth oxalates, separating the oxalate sludge, washing and calcining according to the invention, decompose the concentrate with 1-2 N nitrogen or hydrochloric acid in the presence of oxalic acid, which is taken in the amount of 10-50 wt.% in excess of stoichiometry on oxides of rare-earth elements. The solution of this task is also achieved by the fact that the concentrate is treated with nitric or hydrochloric acid at T: W = 1:  

Describe the basis of extraction and ion-exchange processes in the mineral raw materials processing.

     The method of extraction extraction from ores and concentrates includes grinding ores, leaching, extraction, reextraction of metals, washing the waste cake. Grinding is carried out by the method of dry grinding to a particle size of 0.1-1.0 mm. Leaching is performed by mixing with concentrated acids with a water content of not more than 20%. Extraction is carried out with extractant solutions in an ozone-safe non-combustible diluent pre-saturated with acids to a concentration of 0.2-0.3 g-eq / l. Flushing waste cake spend ozone-safe non-flammable diluent with its subsequent distillation.     The method includes fine grinding of ore, sulfuric acid leaching in the presence of an oxidizing agent, dilution of the pulp, countercurrent extraction, then re-extraction.

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