An Effective Leaching Method to High-Content Tungsten Ore

The main raw materials for the metallurgy of tungsten are wolframite and scheelite. However, with the exploitation of tungsten resources, the grades of the tungsten resources are reduced, the composition of the components is complicated, and associated with other metals, which makes the cost of tungsten ore metallurgy increase. 

The common method for treating the wolframite and scheelite is pressure alkali leaching. Under the conditions of high alkali, high temperature and high pressure, the tungsten ore can be decomposed, and the tungsten content in the slag is reduced to below 1 to 3%, but the conditions and equipments required for the process are harsh, and the process cannot break the barite structure and is not suitable for the high-tungsten-content tungsten ore.

Considering the current issues of  extracting tungsten from high-content tungsten ore, some scholars have provided a method for effectively breaking the structure of high-content tungsten ore and efficiently leaching tungsten ore, which is simple in operation, low in cost, and meets industrial requirements. The specific process is as follows:

500 g of a sorghum tungsten ore was pulverized to a particle size of 74 to 200 μm, mixed with 270 g of Na₂CO₃ and 40 g of SiO₂, and then placed in a corundum crucible and baked in a muffle furnace at 850 ° C for 3 h. The calcined sand was cooled and crushed to a particle size of 0.1 mm to 1 mm, and then a solution of 10 g/L NaCO₃ was used, and the liquid-solid ratio was controlled at 5 mL/g, and leached at 60 ° C for 1 h. The obtained sodium tungstate solution extracts tungsten by ion exchange or extraction.

After the leaching, the tugsten content in the leachate and the leaching slag was analyzed, and the tungsten leaching rate was 95.96%. During the calcination process, Ca, Ba and Si form relatively stable (Ba,Ca)₂SiO₄, and the formation of the substance directly destroys the BaSO₄ structure, and at the same time, the problem of high W loss caused by the precipitation of white tungsten during the ingress and exit process can be reduced.

The technical difficulty solved by the above process is by adding proper amount of Na₂CO₃ and SiO₂ during the roasting process of sorghum tungsten ore can effectively destroy the structure of the original sorghum tungsten ore (the original structure is barite, which is wrapped or dispersed in tungsten ore). ), Ba, Ca and Si in the sorghum tungsten ore are more stable (Ba,Ca)₂SiO₄, and leaching with a high concentration of sodium carbonate solution can effectively prevent the dissolution of CaSiO₃ and the like, and further inhibit the precipitation of tungsten, Increased leaching rate of tungsten. Therefore, the method can fully realize the high-efficiency extraction of tungsten in the low-grade high-content tungsten ore which is difficult to utilize, and the auxiliary additive used is cheap, the process is simple, and fully meets the requirements of industrial production.

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