# Sintering with Sodium Carbonate and Leaching of Wolframite Cakes
###### Abstract  
Focus on the processing of tungsten raw materials through various operations, including sintering, leaching, purification, and the production of technical tungsten acid. Modern research aims to enhance these processes, particularly the sintering of wolframite concentrates with alkali metal compounds and the leaching of concentrates and cakes. Experiments revealed that reactions between tungsten minerals and sodium carbonate from Akchatau ores commence at temperatures above 520-550 \({}^{\circ}\)C, intensifying between 750 and 850 \({}^{\circ}\)C. The concentrates were sintered at 750, 800, and 850 \({}^{\circ}\)C with a sodium carbonate excess coefficient of 1.05 to 1.2 to evaluate the effect on sodium tungstate extraction. Water leaching was conducted under a probabilistic-deterministic experimental design, analyzing five factors at four levels. Tungsten extraction was assessed based on solution density and the composition of the insoluble residue. Data processing established polynomial trends for tungsten trioxide extraction, and a material balance for sinter leaching was calculated from experiments using 100 g samples with a liquid-to-solid ratio of 2:1. The findings can be applied to improve tungsten processing technologies.  
wolframite; scheelite; sodium carbonate; sintering; leaching; electro dialysis Article  
Sintering with Sodium Carbonate and Leaching of Cakes  
[PERSON], [PERSON], [PERSON], [PERSON], [PERSON], G.  
acid to produce tungstc acid. During the processing of the wolframite concentrate, it was found that the charge must be sintered at 450-500 \({}^{\circ}\)C, with the following ratio of components: wolframite concentrate, sodium carbonate, potassium carbonate, and nitrate in the proportion of 1:0.45:0.9:1.  
The results of the assessment of the mechanism and kinetics of the thermochemical interaction of wolframite and concentrates with sodium and potassium carbonates were presented in the works of [PERSON] et al. [15]. It has been shown, using the methods of differential thermal and phase analysis of sintering products, that the interaction of wolframite with sodium and potassium carbonates begins above 723-743 K and is accompanied by the formation of alkali metal tungstates and ferrites.  
Publication [16] presents the rationale for the technology intended to process low-quality wolframite concentrates based on sintering with Na\({}_{2}\)CO\({}_{3}\) and K\({}_{2}\)CO\({}_{3}\) and conducted model experiments with the use of the mathematical planning method. The authors determined particular dependencies linking the degree of extraction (\(\gamma\)) of tungsten into the solution during leaching with the amount (Q) of introduced alkali metal carbonates at the sintering stage, temperature (T), and process duration (\(\tau\)).  
The composition of the initial concentrates and literature data confirm that for Akchatau tungsten concentrates, the most appropriate technology is sintering with sodium carbonate, leaching of the cake with water, and separation of tungsten acid with the subsequent production of tungsten trioxide and tungsten carbide.