Chemical Beneficiation Process for White Tungsten Ore

The chemical beneficiation process for white tungsten ore is a mineral processing technique that exploits the differences in chemical properties between white tungsten ore and gangue minerals. It involves converting white tungsten ore into soluble compounds through chemical reactions, followed by separation and purification to obtain tungsten products. This process is suitable for treating low-grade, complex, and difficult-to-process white tungsten ore, as well as white tungsten concentrate requiring further purification. It effectively addresses resource recovery and deep purification challenges that are difficult to resolve through physical beneficiation methods.

After years of development, chemical beneficiation of wolframite has evolved into a variety of mature processes, including hydrochloric acid decomposition, caustic soda leaching, soda solution pressure cooking, and fluoride salt decomposition. Each process has its own unique principles, operational procedures, and suitable applications.

I. Principles of Chemical Beneficiation of White Tungsten Ore

The core principle of chemical beneficiation of white tungsten ore is based on the chemical properties of the ore. By using specific chemical reagents and reaction conditions, the ore undergoes decomposition reactions, converting into soluble tungsten compounds, while gangue minerals remain in a solid state or are converted into insoluble compounds. Subsequently, solid-liquid separation is used to separate the tungsten from the gangue, followed by purification and crystallization of the tungsten-containing solution to obtain the tungsten product.

The chemical properties of white tungsten ore provide the foundation for chemical beneficiation. Its main component is calcium tungstate, which possesses a certain degree of chemical reactivity and can undergo decomposition reactions with reagents such as acids and alkalis. In contrast, gangue minerals—such as silicate minerals like quartz and feldspar—are chemically stable and do not readily react under conventional chemical beneficiation conditions, thereby providing the prerequisite for chemical separation. The key to chemical beneficiation lies in selecting appropriate chemical reagents and controlling reaction conditions (temperature, pressure, time, etc.) to ensure thorough decomposition of wolframite while minimizing reagent consumption and environmental impact.

II. Process Methods for Chemical Beneficiation of Wolframite

(1) Hydrochloric Acid Decomposition Method

The hydrochloric acid decomposition method is one of the most widely used processes in the chemical beneficiation of wolframite. Its core principle involves utilizing a double decomposition reaction between hydrochloric acid and wolframite to convert wolframite into tungstic acid and soluble calcium chloride. This process features a short reaction time, high decomposition efficiency, and mature industrial technology, making it suitable for high-purity wolframite or scenarios where the purity requirements for the final product are not extremely stringent.

The reaction principle of the hydrochloric acid decomposition method is as follows: under specific conditions, wolframite reacts with hydrochloric acid to form tungstic acid precipitate and a calcium chloride solution. After filtration, washing, and drying, the tungstic acid can be used directly as a product or further processed into other tungsten products such as ammonium metatungstate. The advantages of this method include the ease of the decomposition reaction, with a decomposition rate exceeding 99%, as well as the widespread availability and low cost of hydrochloric acid. The process is simple, easy to operate, and requires no complex equipment. However, the hydrochloric acid decomposition method also has certain limitations, such as high demands on equipment corrosion resistance, necessitating the use of acid-resistant equipment; the reaction generates hydrogen chloride gas, requiring corresponding exhaust gas treatment equipment to prevent environmental pollution; for ores containing high levels of impurities such as carbonates, a large amount of hydrochloric acid is consumed, thereby increasing production costs.

(2) Sodium Hydroxide Leaching Method

The sodium hydroxide leaching method was originally used primarily for the decomposition of black wolframite. With the development of smelting technology, it has been optimized and is now widely applied to the processing of white wolframite. Its core principle involves the reaction of caustic soda with white wolframite under specific conditions to produce soluble sodium tungstate and calcium hydroxide precipitate. Through solid-liquid separation, a tungsten-containing solution is obtained, which is then purified and crystallized to yield tungsten products.

A significant advantage of this method is its compatibility with existing alkali-based production lines, eliminating the need for large-scale equipment retrofitting. For enterprises already equipped with alkali-based smelting facilities, its implementation involves low costs and offers substantial economic benefits.

(3) Soda Solution Autoclaving Process

The soda solution autoclaving process is an effective chemical beneficiation method for treating low-grade white wolframite. Its core principle involves reacting soda (sodium carbonate) with white wolframite under high-temperature, high-pressure conditions to produce soluble sodium tungstate and calcium carbonate precipitates, thereby achieving the separation of tungsten from gangue. This method can effectively process low-grade, complex, and difficult-to-process white wolframite, and under appropriate controlled conditions, high leaching rates can be achieved.

(4) Fluoride Salt Decomposition Method

The fluoride salt decomposition method is a highly efficient chemical beneficiation process for white tungsten ore. Its core principle involves using fluoride salts such as sodium fluoride or ammonium fluoride as decomposition agents to react with white tungsten ore, generating soluble sodium tungstate and calcium fluoride precipitates, thereby achieving the separation and recovery of tungsten. This method offers significant advantages, including high decomposition rates, short reaction times, and low fluoride salt consumption. Furthermore, the filtrate is relatively pure, and the calcium fluoride residue can be recycled, resulting in outstanding environmental benefits.

The reaction conditions for the fluoride salt decomposition method are relatively mild, requiring no high temperatures or pressures. Efficient decomposition can be achieved at room temperature or lower temperatures, with a decomposition rate consistently stable at around 99%.