The main advantages of the thiourea method are: 1) Non-toxic, no neutralization process is required before gold leaching, and cyanide is highly toxic, and a large amount of lime is added for pretreatment before cyanidation. 2) The thiourea regeneration and purification process is simple. 3) The dissolution rate of gold and silver is fast, generally 8 to 10 times faster than the cyanidation method, especially the dissolution of silver, which is far better than the cyanidation method. In the presence of SO 2 , the leaching rate of thiourea It is roughly the same as the cyanidation method. 4) Some impurities in raw materials, such as copper , arsenic , antimony, etc., are not as sensitive as cyanidation. The thiourea method is the most promising treatment for ore that is not suitable for cyanide leaching, especially those complex refractory ore and silver-bearing ore that have been pretreated by bacterial leaching or pressure leaching. However, the thiourea method has the following two disadvantages: one is that thiourea is easily oxidized, resulting in excessive consumption of thiourea, and the other is that thiourea is relatively expensive, and economically it is still competitive with cyanidation. Recent studies have shown that the introduction of SO 2 while controlling the pH of the medium can inhibit the oxidative decomposition of thiourea, reduce the consumption of thiourea to about 1/5, and treat some acidic gold ore with modified thiourea. It is cheaper than using cyanidation.
Lead Based Compound Stabilizer For PVC Foaming Panel
Lead based composite stabilizer for PVC foam board is a commonly used additive used to stabilize the thermal stability of PVC materials during processing and use. Lead based composite stabilizers can effectively inhibit the thermal decomposition reaction of PVC materials, prevent their degradation and yellowing at high temperatures, and thus extend the service life of PVC foam boards. Lead based composite stabilizers play a crucial role in the production process of PVC foam boards. It can improve the thermal stability of materials, extend their service life, and improve their mechanical properties and surface quality. With the continuous development of technology, the performance of lead based composite stabilizers will be further improved, providing better protection for the application of PVC foam boards.
Additives for thermal decomposition of PVC materials,Lubricity,Mechanical properties
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