The geological survey data, associated mainly of silver ore in a variety of filling and replacement hydrothermal deposits of copper, lead, zinc, the contact skarn account type, lamellar or laminar-like deposits, and pyrite type copper sulfide In a nickel deposit. According to preliminary statistics, silver is associated with 57.4% in lead-zinc deposits and 34% in copper deposits. g%, accounting for 1.7% in quartz vein deposits, and others accounting for 6%.
Currently associated silver ore beneficiation of copper, lead and zinc, their general conditions and reagent system is the primary metal sorting is not selected the single silver concentrate, usually silver enriched in lead, zinc, copper concentrate In the mine, it is then recovered through smelting. However, in the smelting process, the silver in the lead concentrate enters the crude lead with the main metal; the silver in the copper concentrate enters the matte, and the recovery process is simple, the cost is low, and the recovery rate is high. The silver in the zinc concentrate, whether using the fire method or the wet process, enters the slag, and the recovery process by the tobacco method is complicated, the cost is high, and the recovery rate is low. Therefore, mineral processing should concentrate silver in lead and copper concentrates.
1. Occurrence and characteristics of silver minerals in lead, zinc and copper ores
Silver is mainly present as an independent silver mineral. Various sulfur compounds and silver, copper, lead, tin, antimony, tellurium, selenium, arsenic and other elements found in a variety of deposits formed in common are: a spiral-shaped sulfur argentite silver, copper silver Hui, Deep red silver mine, brittle silver mine, light red silver mine, sulphur-copper-copper-silver mine, sulphur-lead-lead-silver mine, bismuth-lead-silver mine, strontium-silver mine, selenium-silver mine, etc. A small portion of silver is present in the ore, such as natural silver. There is also a small amount of silver that does not have an independent form in the ore, but forms similarities in the crystal lattice of other minerals, such as silver-gold ore, silver-bismuth copper ore. Silver is present in various types of lead-zinc or copper-bearing lead-zinc pyrite in a variety of different mineral forms.
Various silver minerals are closely symbiotic with sulfide minerals such as lead, zinc and copper, and are mostly fine-grained inlays. The particle size is almost below 0.04 mm, and the size of most silver minerals is 0.04-0.02. In millimeters, the finest is only 0.001 mm. The fine silver minerals are distributed in galena, sphalerite and copper sulfide minerals in the form of continuum, inclusions and microscopic bodies. During the flotation process, sulfide minerals that are closely related to silver minerals become their carriers, enriching silver into various concentrate products. Therefore, the occurrence and embedding properties of silver minerals have a major impact on the comprehensive recovery of silver.
2. Practice of improving the recovery rate of silver in lead, zinc and copper ore
In recent years, due to the rapid increase in the demand for silver and the rise in the price of silver, widespread attention has been paid to the comprehensive recovery of associated silver in lead, zinc and copper polymetallic sulphide ore. In order to obtain the best technical and economic indicators for comprehensive recovery of mineral processing, people have strengthened the research on silver mineral technology, continuously improved the beneficiation process and pharmaceutical system, and kept the ore dressing indicators of lead, zinc and copper sulfide ore at the original level or improved. On the basis of this, the recovery rate of associated silver is increased from 30 to 50% to 60-80%, and the production of associated silver and the level of comprehensive recovery technology have been greatly improved.
a Reforming the grinding process and improving the fineness of grinding are one of the main measures to improve the recovery index of associated silver. Various silver minerals are mostly fine-grained in the lead-zinc-copper polymetallic ore, which are closely symbiotic. The existing grinding conditions are mostly considered from the perspective of recovering lead-zinc-copper sulfide minerals, and it is difficult to make the silver minerals fully monomeric. from. In order to improve the recovery index of associated silver, it is necessary to reform the original grinding process and improve the fineness of grinding. Of course, the choice of grinding process and fineness should consider the possibility of technology and the scientific nature of the process, but also consider the economic rationality. At present, some factories have improved the grinding fineness under the condition of technical conditions, and all the indicators have been improved. For example, the original ore of the Bajiazi lead-zinc mine was changed from one grinding to two-stage grinding. The grinding fineness was increased from 65% to 80%-200 mesh, and the total silver recovery rate was increased by 3.61%. The grinding of Qixia Mountain The fineness was increased from 55% to 65%-200 mesh, the silver recovery rate was increased by 1.24%, and the lead recovery rate was increased by 3.37%. Some factories have added copper-lead or lead-neutral re-grinding. For example, the Shuikoushan lead-zinc mine will use the coarse sweeping in the lead flotation circuit and the finely selected foam to be refracted and returned to the lead roughing operation to make the associated gold. The recovery rate of silver increased by 6.23% and 3.40%, respectively, and the lead and zinc beneficiation index was also improved. The Fozi Chong Pb-Zn Mine River three-point mine has adopted copper-lead mixed-choice and medium-mineral re-grinding, which has increased the recovery rates of lead, zinc and silver by 3.00%. 2.31% and 4.71%, the zinc content of lead concentrate decreased from 5.15% to 4.50%.
b Use cyanide-free or micro-cyanide process. In the flotation process, cyanide which inhibits silver minerals or carrier minerals is not used or used, which is advantageous for the recovery of associated silver. For example, Xilin lead-zinc mine, ore dressing cancels the original cyanide and reduces the amount of lime used by more than half. The recovery rate of silver in lead concentrate reaches 71.6%, which is less than cyanide (to g/ton) and polycyanide (150 g). / ton) increased by 5.6% and lO respectively during flotation. 99%, while the loss of silver in tailings towels decreased by 3.67% and 11.83%, respectively. Another example is the Qixiashan lead-zinc mine. In 1079, the pre-removal of easy-floating minerals and cyanide-free flotation process was adopted to increase the recovery rate of silver in lead concentrate by about 5%, and the recovery rates of lead, zinc and sulfur were different. Improvement. In 1970, the Bajiazi lead-zinc mine changed the flotation process from cyanide to microcyanide, and the amount of cyanide was reduced from 300 g/ton to 3-5 g/ton, resulting in 37% recovery of associated silver. Increased to 52%, while low-grade copper was also recovered and solved the problem of tailing water pollution. In short, the use of cyanide-free or micro-cyanide process is beneficial to improve the comprehensive recovery index of silver. This process has received extensive attention, and more than 60% of lead-zinc-copper mines have been applied and achieved good results.
Type collector C and increased more collectors with the use. In the past, the commonly used collectors for the flotation of lead-zinc polymetallic sulfide ore in China were xanthate (ethyl, butyl) and black medicine (No. 25, No. 31). In recent years, butylammonium black has gradually become one of the main collectors for the flotation of lead-zinc polymetallic sulfide ore. It not only has better selectivity, but also shows a strong ability to capture silver minerals. In addition, the use of butyl ammonium black medicine with xanthate, ethyl sulfide, esters and other collectors has a good effect on the improvement of mineral processing indicators such as associated silver and lead and zinc. It has been widely used in flotation practice. For example: Bajiazi lead-zinc mine, copper-lead mixed operation with butylammonium black drug instead of No. 31 black drug, the total silver recovery rate increased by 6.75%; Xiangxi lead-zinc mine with butylammonium black drug and aniline black The ratio of 1:1 is mixed and used. Under the condition of natural pH, the copper and lead are mixed. The total recovery rate of associated silver is increased by 2l%, and the recovery rate of copper is also improved. Xilin lead-zinc mine started in 1980. The use of butylammonium black in low alkalinity, and the use of zinc sulfate, sodium carbonate and zinc-lead lead process, the recovery of silver in lead concentrate increased by 10.99%, while gold also got a part Recycling.
d Improve the beneficiation process. The selection of the mineral processing process should take into account the high-precision indicators of lead metal, lead and zinc, as well as the comprehensive recovery of associated silver, so that the useful minerals can be recycled to the maximum extent. For silver-containing lead-zinc polymetallic sulfide ore, if the embedding characteristics of the associated silver are considered, the mixed flotation or partial mixing flotation process is beneficial to the comprehensive recovery of the associated silver. However, the determination of the flotation process is determined by various factors, and the nature of the ore is the basis. Therefore, each selection plant should be tested, repeated production practices, and gradually improve the existing process. At present, the processing plants for the treatment of lead-zinc or lead-zinc pyrite types are mainly lead-based and other floatable processes, such as Dongbo Nonferrous Mines Pheasant Tailings Plant, Huangshaping Lead-Zinc Mine, etc. Flotation process, such as Fankou lead-zinc mine, Mengenjiali cover, Yinshan lead-zinc mine, Dongbo non-ferrous mine Chaishan plant, etc.; Shuikoushan lead-zinc mine adopts preferential lead, zinc-sulfur mixed separation Process flow. The processing plant for the treatment of copper-lead-zinc-pyrite type is mainly based on partial mixing, partial separation or partial mixing and prioritization. The former such as Bajiazi, Qixiashan, Xiangyu lead-zinc mine, etc.; the latter such as Tongshanling non-ferrous ore, Fozi Chong lead-zinc mine three sub-mine. The Xiaotieshan lead-zinc mine is a full flotation process. Production practice shows that changing the process according to the nature of the ore is conducive to the improvement of the comprehensive recovery index of mineral processing.
3. Overview of the main domestic lead-zinc-copper polymetallic sulfide ore recovery silver (see Table 33.5.56).
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