Current Status and Problems of Tin Mine Resources Utilization in China

I. Resource reserves and their characteristics

Of tin ore is rich in resources, as of the end of 2007, China's tin proved reserves 4,836,600 tons, of which the foundation reserves 1,522,500 tons, accounting for 31.5%, to identify resources 3.3141 million tons. China's tin mines are mainly concentrated in Yunnan (1,439,900 tons), Guangxi (975,500 tons), Hunan (917,700 tons), Inner Mongolia (78,100 tons), Guangdong (560,100 tons) and Jiangxi (249,900 tons), these six The reserves of tin mine resources in the provinces accounted for 97.89% of the nationally identified resource reserves.

The sand-tin ore is mainly distributed in the metallogenic area of ​​the South China Tin Mine, and the primary ore is concentrated in the vicinity of the Tropic of Cancer. For example, the old factories in Yunnan, the large factories in Guangxi, and the Nanling Mountains at the junction of Guangdong and Guangxi.

Second, the status quo of development and utilization and the utilization of resources in the development process

As of the end of 2007, China's tin mines have utilized 245 mining areas, occupying 3.602 million tons of identified resource reserves, accounting for 74.44% of the country's identified resource reserves. Among them, the basic reserves are 1,296,900 tons, accounting for 85.2% of the national basic reserves. Yunnan's Gejiu and Guangxi's big factories are China's two major tin mine production bases. There are not many mines that can be planned and utilized, 57; the resource reserves are small, 813,500 tons, of which the basic reserves are 193,300 tons, accounting for 16.8% and 14.9% of the national total.

The concentration of tin mine production in China has increased. At present, there are 153 tin mines, including 2 large mines, accounting for 1.3% of the total number of mines; 11 medium-sized mines, accounting for 7.2%; 56 small mines, accounting for 36.6%; and 84 mines below the scale, accounting for 54.9%.

In 2007, the output of tin concentrates in the country was 163,000 tons. Among them, the output of Yunnan, Guangxi and Hunan provinces was about 72,500 tons, accounting for 44.5% of the national total. Jiangxi (3,149 tons) is also the tin concentrate production exceeding 1,000 tons.

In 2007, the average technical index of tin mine mining in China: 0.56% of the ore grade and 98% of the mining recovery rate; the average technical index of pit mining: 0.66% of the ore grade, the mining recovery rate is 91.79%, and the ore depletion rate is 10.12%; Calculated according to the 20% of the total production volume of the exposed ore, the average mining recovery rate should be: 93%; the national average of the main technology of mineral processing : 0.62% of the original ore grade, 44.19% of the concentrate grade, 65.45% of the actual ore dressing rate, tail The ore grade is 0.21%. The main technical indicators of tin smelting: the total recovery rate of smelting is 96.79%. The resource utilization rate in the design stage is calculated on the basis of 80% on average. The comprehensive utilization rate of tin resources in China is 80% × 93% × 65.45% × 96.79% = 47.13%.

In the process of tin mining, there have been vicious incidents that have shocked China and foreign countries and seriously damaged resources. Dachang Tin District # 100 orebody is rare at home and abroad large special tin-rich multi-metal ore, ore reserves of 10.76 million tons, tin, lead, zinc, antimony, silver, molybdenum average grade of 1.5% and 49% 11.2%, 4.88%, 153g/t and 0.02%, the overall average grade of metal is as high as 22.54%, and the above five kinds of mineral metal reserves are 2.425 million tons, including 220,000 tons of tin, 1.1 million tons of zinc, 590,000 tons of zinc, silver. 1824 tons, indium 21520 tons, the potential value of resources exceeds 20 billion yuan. The original design was mined for 37 years. However, in the mining area, more than 50 illegal civilian mines have been plundered and stolen, and there are hundreds of holes in the mining area. The ore reserves of the mines at the end of 2000 were only 2.4 million tons. It is estimated that there will be 2 to 3 years of closed pits. The mine has a shortened life of at least 20 years. Crazy piracy has caused more than 10 million upstarts in Nandan County, where the mining area is located, among which there are many individual mine owners with assets of 100 million yuan. In July 2001, the ore body suffered heavy mining accidents due to the exploration of the private enterprises in the deep penetration of the water layer, and was permanently closed by the relevant state departments.

Third, comprehensive utilization: achievements and deficiencies

School of tin mostly tin-copper deposit was allowed to warm, skarn iron deposit tin, lead and zinc deposit hydrothermal tin, hydrothermal vein cassiterite - quartz deposits and cassiterite - sulfide deposits, in Low temperature-high medium temperature hot liquid metasomatic deposits, alluvial sand deposits, etc. Tin is mainly associated with iron ore and tungsten ore, and is associated with copper, iron, antimony, lead and zinc.

Compared with the world tin mines, China's tin mines are rich in resources and have many outstanding features:

(1) There are many associated components. China's tin mines account for only 12% of the output as a single mineral. The tin mines as the main minerals account for 66% of the country's total reserves. Tin ore, which is a companion component, accounts for 22% of the country's total reserves. Symbiotic and associated minerals mainly copper, lead, zinc, tungsten, antimony, molybdenum, bismuth, silver, niobium, tantalum, beryllium, gallium, germanium, cadmium, and iron, sulfur, fluorite and the like.

(2) The singularity of useful tin minerals and the diversification of useful associated minerals: tin minerals with industrial value are almost only one type of cassiterite, while the useful minerals associated with ore are 3-4 types, and more than a dozen .

(3) The value of the associated elements in most tin mines exceeds the value of the main metal tin, but such ore needs to be treated with a beneficiation process and a combined metallurgical process with high process costs and high separation and recovery effects. In China, the utilization level of the associated resources of tin mines is relatively high in large tin mining enterprises. In terms of process flow, flotation is generally used to select concentrates of lead, zinc, copper and antimony, and the tailings of flotation are recovered by re-election. If there are more than one element associated with it, a complex process is required. It is difficult for small and medium-sized tin mines to master this technology. Therefore, in actual production, only small or medium-sized mines recover only one or two kinds of symbiotic elements, and other associated elements are lost in the tailings.

According to the “National Non-oil and Mineral Resources Development and Utilization Statistics Annual Report” of the Development Department of the Ministry of Land and Resources, the comprehensive utilization value of the tin mining industry in 2007 was 561.5 million yuan, accounting for 13.25% of the total industrial output value.

As the two largest tin mining companies in China, Yunnan Tin Industry Co., Ltd. and Liuzhou Huaxi Group attach great importance to the comprehensive utilization of the associated resources of tin mines, and have invested a large amount of manpower, material resources and financial resources to conduct scientific research and have achieved great results. In the case of mineral processing, there are unique processes for the recovery of co-associated elements for various ore types. In addition, since the company has its own smelter, it comprehensively recovers the associated elements through the combined process of mineral processing, metallurgy or metallurgy, with high comprehensive utilization and high recovery rate. In handling the old tin mine, Yunxi Company also recovers copper, lead, zinc, tungsten, antimony , silver, indium, cadmium, arsenic , iron and sulfur in addition to tin. The utilization rate of main and symbiotic mineral resources in the design stage of the mine is: 85% tin, 80% copper, 80% lead. The actual utilization rate of main and symbiotic minerals is 80% for tin, copper and lead. The recovery rate of tin is 65.89%. 76.16%, the actual recovery rate of associated elements recovered in the smelting stage is 65% arsenic, 50% bismuth, 80% copper, and 72% indium.

The actual utilization rate of the main mines and symbiotic minerals (tin, lead, zinc and antimony) of Liuxi is 90.5%, and the mining recovery rate is 98%. The recovery rate of ore recovery is 70.13%, lead 92.23%, zinc 86.64%, 锑90.22%, concentrate grade tin 52.89%, lead 30.37%, zinc 46.99%, bismuth 26.33%, tailings grade tin 0.61%, lead 0.84%, zinc 2.63%, 锑 0.94%. The important co-associated elements that are currently not selected in the existing beneficiation process are only arsenic and cadmium.

Comprehensive recycling Pinggui Bureau of Mines also do better, in addition to the recovery of tin, but also the recovery of tungsten, thorium, bismuth, indium, arsenic, silver, copper, gold, lead elements.

There is a problem:

(1) The utilization level of mining, mining and smelting in tin mines in China is uneven, and the overall level needs to be improved. In particular, the overall level of mining is low. Due to the main mining veins, most of the ore bodies are not thick enough, and the extension is limited. Due to resource constraints, the mining volume of individual ore bodies is not large, so the degree of mechanization and labor productivity are low, especially for small and medium tin mining enterprises. The mining method was originally used even by pushing the back of the person. Large enterprises are contracted to individuals due to the implementation of contracting mechanisms.

In terms of mineral processing, the overall level is acceptable. The state has invested heavily in technological transformation of large-scale tin mining enterprises. There are some mineral processing equipment with independent property rights, especially re-election equipment , and the results are better promoted. However, it should not be overlooked that some small and medium-sized tin mines are at the expense of one-sided cost reduction and waste of resources, resulting in a surprisingly low recovery rate. In addition, equipment aging problems are common in various plants. In terms of metallurgy and comprehensive utilization, the level of each mining enterprise is very different. Large-scale tin mining enterprises are very high-level, and basically can recover what elements have valuable elements, but the utilization level of small and medium-sized tin mining enterprises is very low, and the symbiotic minerals are partially utilized, and the associated elements are basically at the level of no utilization. .

(2) The symbiotic tin resources of some large polymetallic mines have not been fully utilized. The Shizhuyuan Mine is a prominent example of the decision to launch a mine in the case that the metallurgical technology has not yet fully passed. The mine is called a tungsten-tin polymetallic mine, but it does not produce tin.

The Shizhuyuan Mine is known as the Kingdom of Nonferrous Metals. The mine has four ore belts, of which the No. 1 ore body is a fine vein-filled marble -type tin ore belt, the No. 2 ore body is a skarn-type W-Bi ore belt, and the No. 3 ore body is a Yunying rock network. - The skarn type W-M0-Bi ore belt and the No. 4 ore body are the Yunying rock type W-Sn-Mo-Bi ore belt. The mine is only a very large tin deposit in terms of cassiterite, but due to the low grade of Sn, fine grain size of cassiterite, low recovery rate of laboratory test beneficiation (selected grade 0.26%, concentrate grade 50.94%, recovery rate 30%) It was listed as off-balance sheet reserves, and the supplementary survey results showed that the amount of Sn metal was 486,500 tons. In addition to the main ore, there is an independent pheasant tail Cu-Sn ore body.

The No. I ore body of the No. I belt is actually an independent single tin ore body. The ore geological grade: Sn 0.169%, proven reserves of 84.33 million tons, equivalent to 140,000 tons of Sn metal. Due to its low grade, the size of the cassiterite is small and has not been exploited. The seriousness of the problem lies in the fact that the Shizhuyuan Mine is currently producing the No. III ore body with a design period of 16 years. According to the current mining speed, it will be converted to the No. II ore body in less than 16 years. The No. II ore body is designed to be exposed. When the No. I ore body that is on the upper side cannot be used by the industry, all the stripping will be treated as waste rock. In this way, 140,000 tons of metal tin will be destroyed. From the strategic consideration of making full use of tin resources, it is necessary to conduct feasibility study on the development of tin resources as early as possible. However, the traditional sorting process has low recovery rate and poor economic benefits, so it is necessary to innovate the beneficiation process in order to fully utilize the No. I ore body tin. The purpose of the resource.

Even the No. 3 ore body currently being produced is not ideal for the comprehensive utilization of symbiotic mines. The ore body has a symbiotic Sn metal reserve of 108,300 tons, which are all refractory off-balance sheet mines and have not been comprehensively utilized so far. In the past, the problem was only considered from the height of Sn, that is, how to reduce Sn in W concentrate, and did not consider the utilization of this part of difficult-to-select tin resources. When the No. 3 ore body is finished, more than 100,000 tons of metal Sn will also enter the tailings pool. How to realize the comprehensive recycling of difficult-to-select tin resources from the level of improving the technology of metallurgy is another major practical problem in the development of Shizhuyuan Mine.

The Dongcheng lead-zinc polymetallic ore belongs to the Shizhuyuan Mine. After the selection of lead and zinc, the tailings contain up to 2.5% of Sn, which has not been comprehensively recycled. The tailings dam was later destroyed by a flash flood, and the tin resources were lost. This can be regarded as a lesson in the failure to deal with difficult resources in a timely manner.

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