Research has been carried out on three different technological approaches to the processing of synnyrites, namely:
  • Scheme №1 – sulfuric acid technology for processing synnyrites according to the dolomite scheme
  • Scheme №2 – sulfuric acid technology for processing synnyrites according to the lime scheme
  • Scheme №3 – technology for processing synnyrites according to the alkaline scheme

For each of the presented schemes done:

  • Scientific research work (R&D) with the determination of the degree of extraction of target components into finished products;
  • On the basis of research and development, material balances were built for each of the planned technological conversions, on the basis of which, in turn, capital and operating costs were determined;
  • The data on the quality of the commercial products planned for production were obtained, on the basis of which the analysis of potential consumers was carried out;
  • Requirements for the production site with the definition of requirements for connecting gas, energy;
  • Principal and hardware diagrams;
  • Financial model with the definition of the payback period of the project.

Based on the SWOT analysis, it was found that the most effective scheme is No. 3, which has not only the minimum payback period, but also has a number of advantages over acid analogues, in particular:

  • Possibility of obtaining any potassium salts by acidic (sulfate / nitric acid) neutralization of potash solution obtained after the 2nd stage of carbonization;
  • Ability to adapt to the needs of the potash products market by varying the consumption of acids;
  • Ability to concentrate target components in circulating solutions, which reduces the cost of evaporation;
  • Working with alkaline streams does not require expensive acid-resistant equipment;
  • Capital costs are 1.5-2.0 times lower relative to acidic schemes;
  • Availability of engineering companies on the market that are ready to supply a similar production on a turnkey basis;
  • Possibility of locating production facilities at the deposit due to the use of pulverized coal fuel (PFC) and the presence of significant limestone reserves in the shoulder accessibility (ore bodies within 5 km and 20 km);
  • High degree of technology development for similar raw materials (nepheline processing);
  • Possibility of selling aluminum hydroxide as a commercial product, which is a semi-finished product in the process of alumina production and has its own sales market.

 

Scheme №1 – Technological block-scheme of synnyrite processing according to the dolomite scheme 

Scheme with sintering synnyrites with dolomite and subsequent sulfate leaching. According to the scheme, microcline decomposition is carried out by a magnesium-containing natural mineral (dolomite) to obtain a solution containing potassium, aluminum and magnesium sulfates. Aluminum and potassium compounds are then precipitated in the form of alum, followed by their decomposition into Al2O3 (alumina) and K2SO4 (potassium sulfate). Magnesium sulfate is isolated from circulating solutions in the form of MgSO4*7H2O (heptahydrate magnesium sulfate), part of which is removed from the system in the form of a commercial product, and part is sent to obtain MgO (magnesium oxide).
 
The end-to-end extraction obtained according to the scheme was:
  • K2O – 94,02%;
  • Al2O3 – 84,91%
  • MgO – 93,87%

Scheme №2 -Technological block-scheme of synnyrite processing according to the dolomite scheme 

Scheme with sintering of synnyrites with limestone and subsequent sulphate leaching. Microcline decomposition is carried out by sintering with limestone. Leaching with sulfuric acid makes it possible to obtain solutions of potassium and aluminum sulfate, from which alum is further precipitated, followed by their decomposition into Al2O3 (alumina) and K2SO4 (potassium sulfate).

 

The end-to-end extraction obtained according to the scheme was:
  • K2O – 88,35%;
  • Al2O3 – 88,20%.

Scheme №3 -Technological block-scheme of synnyrite processing according to the alkaline scheme

Scheme with sintering synnyrites with limestone and subsequent leaching of potassium and aluminum with alkaline circulating solutions. The technology involves the production of K2CO3 (potash) and Al2O3 (alumina). 

The end-to-end extraction obtained according to the scheme was:
  • K2O – 86%;
  • Al2O3 – 83%.
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