Summary of the synthesis method of environmentally friendly gold leaching agent
As the country pays more and more attention to environmental protection, it should be the government’s job to encourage the development of green industrial projects with low pollution intensity and advanced clean production levels, and to promote the implementation of technological measures for relevant environmental protection projects to control and control environmental pollution from the source. focus. With the continuous advancement of mineral processing technology, gold (non-ferrous metal) mineral processing agents are also constantly being introduced and innovated. Low-toxic and environmentally friendly gold extraction agents aimed at replacing sodium cyanide are blooming all over the country. The main ingredients of such agents are: It is formulated with thiocyanate, thiourea, urea and other chemical reagents added with caustic soda. Compared with traditional cyanide, it has lower toxicity and is relatively safe to use. It is of great significance to gold (non-ferrous metal) production and environmental protection.
The synthesis method of producing low-toxic and environmentally friendly gold extraction agent using urea, caustic soda and soda ash as the main raw materials is briefly summarized as follows:
Method 1: Heat urea and soda ash to a molten state in a converter, add yellow blood salt sodium (potassium), stir and melt, then discharge and cool, crush and package; the finished product synthesized by this method was analyzed by X-ray diffraction to determine whether it was synthesized under different conditions. The physical phase of the product, the results show that: the gold leaching agent synthesized from reagents such as yellow blood salt potassium, urea and soda ash is mainly composed of sodium carbonate, sodium cyanate, cementite (Fe3C), and a new phase is also generated. Only use Neither one nor both of the above three reagents can form a new phase. Since all other phases are unable to leach gold, the new phase may have acted as a gold leach agent. Therefore, the coexistence of the three reagents potassium yellow blood salt, urea and soda ash is a necessary condition for the synthesis of an effective gold leachant containing a new phase. The roasting temperature of this method has a significant impact on the roasting effect and the formation of new phases. When the temperature is higher than 550°C, a new phase forms, but at 800°C, the new phase disappears, and the formed new phase may be unstable. This method uses yellow blood salt and potassium, which is expensive and has a high input amount, resulting in high production costs.
Method 2: Heat urea, soda ash, catalyst, and inhibitors to a molten state, keep them warm for a period of time, discharge and cool, crush and package; this method also uses urea and soda ash as the main raw materials, but adding a catalyst can promote the reaction at medium and low temperatures. At the same time, inhibitors are added during the synthesis process to prevent the product from decomposing at relatively high temperatures and causing the disappearance of new phases, which ultimately affects the quality and stability of the product. X-ray diffraction analysis of the finished product synthesized by this method can also reveal new phases that can play the role of gold immersion. The cost of this method is relatively low, the content of active ingredients in the product is controllable, and the content of active ingredients is higher than that of method one.
Method three: react urea, soda ash, and reducing agent in a molten state. After the reaction is completed, cool down, crush and package. This method basically uses urea and soda ash to react at a certain temperature to synthesize sodium cyanate. Reducing agents such as iron powder and reducing carbon powder can reduce sodium cyanate into highly toxic sodium cyanide. This method is relatively low-cost and can synthesize high-content finished products. X-ray diffraction analysis shows that no new phase is formed, mainly sodium cyanide.
The main raw materials of the above three methods are urea and soda ash. A mixture of soda ash and sodium cyanate can also be used as alternative raw materials to avoid the ammonia gas generated by the former reaction from polluting the environment. The reaction equipment of the three methods is the same, and high-temperature electric furnaces or diesel oil can be used. Or gas-fired converter for production.
Post time: May-20-2024
