[nonferrous Changwen] Beneficiation, processing fee formula, import valuation! About the "realization" encyclopedia of lead-zinc mines, there are all here!

As the name implies, lead-zinc ore is a kind of mineral resources rich in lead and zinc elements. Lead-zinc ore resources can be widely used in chemical industry, such as mechanical chemical industry, petrochemical industry and so on. With the deepening of the study of lead-zinc ore technology, the use of lead-zinc ore has been broadened in recent years, but the reserves of lead-zinc deposits in China are relatively small, and at the same time, they are restricted by the mining technology of lead-zinc mines. At present, the mining level of lead-zinc mines in China lags far behind the average level of the world, which not only affects the development and progress of domestic industry, but also raises the price of lead-zinc mines, which is not conducive to the competition in the world market. Throughout the lead-zinc mining areas in China, they are remote areas with complex geological conditions and inconvenient transportation. Therefore, the mining of lead-zinc mines is relatively difficult, which restricts the development of lead-zinc mining industry in China.

Status quo: easy to find, not easy to mine

Characteristics of lead-zinc ores in China:

The main results are as follows: (1) there are many small and medium-sized deposits in lead-zinc mine, and the ore types are complex.

Of all 760 lead deposits in China, large deposits account for only 1.5%, and of all 806 zinc deposits, large deposits account for only 4.5%. Among the more than 700 mining areas in China, the lead and zinc reserves of large and medium-sized deposits account for 81.1% and 88.4%, respectively. There are a variety of ore types, the main ore types are lead sulfide ore, zinc sulfide ore, lead oxide ore, zinc oxide ore, lead-zinc sulfide ore, lead-zinc oxide ore and mixed lead-zinc ore and so on. There are more lead-zinc deposits and copper-zinc deposits dominated by zinc, but few lead-zinc deposits and even less single lead deposits.

(2) there are more poor ore, less rich ore, more complex structure and mineral composition, and less simple.

At present, the average grade of lead and zinc is 3.74%, zinc is higher than lead, the ratio of lead to zinc is 1 to 2.5, and most of them are 1 to 1.2 abroad. The composition of ore is complex, and some of them are more than 30 minerals. Many ores have fine grain size and complex structure, so they belong to the type of refractory ore, which brings difficulties to mineral processing.

(3) the material composition of lead-zinc deposit is complex, there are many associated components, and the comprehensive utilization value is great.

Most of the deposits are commonly associated with elements such as Cu, Fe, S, Ag, Au, Sn, Sb, Mo, W, Hg, Co, Cd, In, Ga, Ge, Se, Tl, Sc and so on. Some deposits mine ores with more than 50 associated elements. In particular, in the past 20 years, through comprehensive exploration and study of ore material composition, it has been confirmed that many lead-zinc deposits contain high silver and become lead-zinc-silver deposits or silver-lead-zinc deposits, and their silver reserves account for more than 60% of the total silver reserves in China. The output of silver recovered comprehensively in the process of mining, separation and metallurgy accounts for 70% to 80% of the national silver output, and the reserves and output of gold are also considerable.

The reasons why it is not easy to mine lead-zinc mines:

1. Since 2017, with the stricter inspection of environmental protection and safety in China, some small mines have been shut down one after another.

2. The production of new mines is not ideal, which is affected by a variety of reasons, and the release of most of the new production capacity is slow. Through investigation and research, it is shown that the mining reserves of some mines are not up to the standard of the mining license and are infinitely delayed. In addition, the mining process related to environmental protection part of the audit efforts, and delayed mining.

3. The grade of in-production mines decreased. Among them, the decline of mine grade in Inner Mongolia is more prominent. Therefore, the self-sufficiency rate of domestic mines is gradually declining, and the dependence on imported mines is gradually increasing. In a short period of time, the shortage of domestic mine supply will not be effectively alleviated.

How to discover lead-zinc ore

Because lead-zinc deposits often contain pyrite, siderite, iron dolomite, iron calcite or sphalerite, they are easy to decompose under oxidation conditions to form deposits such as limonite. Usually, by sampling and testing the iron cap, it is possible to know whether there is a prospecting prospect for lead-zinc deposits in the area. If the content of lead and zinc in the iron cap and oxidation zone is very high, it itself constitutes the oxide of lead and zinc. There is a slight difference in the geochemical behavior of lead and zinc, which makes it possible to separate lead and zinc under oxidation conditions. The oxides of lead are white lead ore, black lead ore, block black lead ore, lead alum and lead alum. Because lead sulfate is generally insoluble, it is dispersed in the oxidation zone, and the migration distance is small, which is close to the original orebody, and sometimes it can be enriched and formed in the residual slope deposit. The oxides of zinc include sphalerite, heteropolar ore, water zinc ore, silicon zinc ore and so on. Because zinc sulfate is soluble and can be migrated for a considerable distance, zinc oxide distributes more widely than lead oxides and is easy to leach and accumulate integrated ores. Therefore, zinc oxide ore is often more valuable than lead oxide ore.

Galena (containing 86.6% lead)

Sphalerite (containing 67.1% zinc)

How to mine after finding the mine?

China's lead and zinc mining, mainly underground mining, a small number of mining areas for open-pit mining or open-pit mining, and then to underground mining. Underground mining, the current mining depth is generally 300 to 800m. According to the topography, orebody occurrence, scale and burial depth of the deposit, four development methods are usually used, such as shaft, flat hole and joint development, and inclined shaft development, according to the topography, orebody occurrence, scale and burial depth of the deposit. Mining methods are divided into: caving method, retention method, filling method, open field method, pillar mining, goaf treatment.

Smelting method of lead-zinc ore

Lead sulfide concentrate is the main mineral raw material for lead smelting, and its smelting methods are fire process and wet process. At present, the fire method is the main method, and the wet method is in the stage of experimental research. The methods of sintering roasting-blast furnace smelting, reaction smelting and precipitation smelting are used in fire lead smelting. The refining of lead is mainly by fire refining, followed by electrolytic refining.

Zinc sulfide concentrate is the main mineral raw material for zinc smelting, as well as fire and wet smelting. Fire smelting adopts vertical tank distillation, flat tank distillation or electric furnace, and wet zinc smelting, which has developed rapidly in the past 20 years, has become the main method of zinc smelting. The crude zinc obtained by fire zinc smelting is refined by distillation or directly applied, while the electrolytic zinc obtained by wet zinc smelting is of high quality and does not need refining.

For the lead-zinc sulfide mixed concentrate which is difficult to separate, the closed blast furnace melting method which produces lead and zinc at the same time is generally used. For the lead-zinc oxide mixed ore, which is extremely difficult to separate, there is a unique treatment method in our country, that is, the original ore of the lead-zinc oxide mixed ore or its enriched products are melted in the blast furnace after sintering or pelletizing in order to obtain crude lead and lead-containing zinc melting slag. The slag is further fumigated in the fuming furnace to obtain zinc oxide products, and electrolytic zinc is obtained by wet zinc smelting. In addition, zinc oxide products can be obtained by direct fumigation in rotary kiln.

The products of lead and zinc concentrate in China are rich in associated components, which have been comprehensively recovered in the smelting process, and the economic benefit is very considerable. Copper, sulfur, zinc, gold, silver, platinum group metals, bismuth, TI, cadmium, selenium, tellurium and other products are comprehensively recovered during lead smelting. When smelting zinc, there are sulfur, lead, copper, gold, silver, indium, gallium, germanium, cadmium, cobalt, TI, Hg and other products.

The first step of "realization" of lead-Zinc Mine-Beneficiation

Lead-zinc ores generally have to be enriched into concentrate in order to smelting lead and zinc metal products. The sulphide ore is usually treated by flotation, the oxidized ore is processed by flotation or gravity separation combined with flotation, or flotation after sulfidation roasting, or reflotation with sulfuric acid after gravity separation. Polymetallic lead-zinc ores are generally processed by magnetic-flotation, gravity-magnetic-flotation and other combined mineral processing methods.

Common flotation process of sulphide ore

Raw ore grade, concentrate grade, tailings grade and actual recovery.

1. Processing fee (domestic 50 grade as the benchmark)

Lead concentrate price (metal tons) = SMM1# lead-processing fee

Zinc concentrate price (metal tons) = SMM1# zinc-processing fee-20% (SMM1# zinc-15000)

Science Popularization: about twenty-eight percent

Because of the high zinc price, the mine and the smelter have reached an agreement to enjoy a share of more than 15000 of the price. The level of processing fees is directly related to the production willingness of the smelter. In theory, if the processing fee falls below the cost line of the smelter, the smelter will reduce its production accordingly. In addition, some precious metals such as silver, indium and gold can be extracted from the concentrate, priced according to the situation, negotiated or deducted in the processing fee, or given to the smelter as a free metal.

Metal content = raw ore quantity * raw ore grade * recovery rate

2. Transportation

Divided into ex-factory price (concentrator) and arrival price (to smelter, including freight)

Transport is often carried by steam / train, some areas are also transported by water, and the freight is calculated by weight in real tons.

Physical tons (dry tons) = raw ore quantity * raw ore grade * recovery rate / concentrate grade.

The "realization" of lead-zinc mines should also be understood: how do imported mines be priced?

In international trade, the valuation of non-ferrous metal minerals generally has a fixed trading practice, that is, based on the corresponding LME metal price.

Zinc concentrate

85% or grade deduction of 8%

[LME Price * Grade * 85%-processing fee] / Grade * tax rate * Exchange rate + miscellaneous fee + combined fee (yuan / metal ton)

Science Popularization: about LME

The London Metal Exchange (LME,), known as London Metal Exchange), is the largest non-ferrous metal exchange in the world. Established in 1876, it is an indirect wholly owned subsidiary of the Hong Kong Stock Exchange. Trading varieties include copper, aluminum, lead, zinc, nickel and aluminum alloys, and exchange prices and inventories have an important impact on the production and sale of non-ferrous metals worldwide.

The prices and inventories of the London Metal Exchange have an important impact on the production and sale of non-ferrous metals worldwide. In the mid-19th century, Britain was the world's largest producer of tin and copper. With the passage of time, industrial demand continues to grow, and Britain urgently needs to import a large number of industrial raw materials from foreign mines. Since the beginning of this century, the London Metal Exchange has publicly published its transaction price and has been widely used as the benchmark price for world metal trade. 70 per cent of the world's copper production is traded on the basis of the official licence price published on the London Metal Exchange.

The London Metal Exchange, the world's largest metal exchange, will accept the renminbi as a pledge for banks and brokers to trade on the platform, the latest step in the globalisation of the renminbi. The London Metal Exchange, which traded $15 trillion in 2014, currently accepts pledge currencies such as the dollar, the euro, sterling and the yen.

Reference: an Analysis of Modern lead-Zinc Mining Technology. Ren Yun. Non-ferrous metal abstracts. August 2015. Volume 30, No. 4

Key points of Beneficiation Technology of complex and Refractory lead-Zinc Mine he Jiangchao. Xie Yan. Science and technology forum

Pay attention to the trend of metal prices in 2019:

What will be the balance between supply and demand in the metal market next year, and how will the price go? Where is the demand growth point? What is the impact of environmental protection? How much impact do the import restrictions on scrap copper have on supply? What is the evolution of industry policy? Please pay attention to the "2018 China Nonferrous Metals Annual meeting and 2019 (SMM) Metal Price Forecast Conference" held in Shanghai on October 19, at which there will be famous macroeconomists, executives of well-known enterprises in various industries, and senior analysts of various metal varieties in SMM. For you a comprehensive analysis of the 2019 metal market. At that time, more than 1000 elites and institutions in the industry will gather together, and more than a dozen well-known media at home and abroad will report on the spot.

"Click to enter the registration channel