[nonferrous Changwen] the development of copper smelting in the world is enough to read the copper smelting process.

SMM news: copper is a prehistoric metal, as early as primitive society has been discovered and used by human beings. Due to the emergence of copper, the Stone Age died out, and mankind gradually entered the Bronze Age.

Copper electrolytic refining was invented in Europe in 1865, which is of great significance to the progress of copper smelting technology.

When it comes to the history of copper smelting in China, we have to mention wet copper, which originated in China and is called "copper leaching in bile water" in ancient times. In the Tang and Song dynasties, it was mainly concentrated in Jiangxi lead Mountain, Dexing and Guangdong Lingshui, with an annual output of nearly 2000 tons. The ancient ore in Tongling area is larger in scale and has a long span of time. It has been the center of copper mining and smelting from Shang and Zhou dynasties to Tang and Song dynasties. The copper industry in modern China was in a backward position. Until 1949, only four factories, Shenyang smelter, Shanghai smelter, Kunming smelter and Chongqing smelter, maintained a small amount of production, with an output of less than 3000 tons. After 1949, the whole industrial level of New China improved rapidly, and large copper smelters such as Tongling, Baiyin, Daye and Yunnan were built.

I. Fire smelting

Fire copper smelting is the main method of copper production, accounting for about 80% of copper output, mainly the treatment of sulphide ore. The advantages of fire copper smelting are strong adaptability of raw materials, low energy consumption, high efficiency and high metal recovery. Fire copper smelting can be divided into two categories: one is the traditional process, such as blast furnace smelting, reflection furnace smelting, electric furnace smelting. Second, modern strengthening process, such as flash furnace smelting, molten pool smelting.

Due to the prominent global energy and environmental problems since the middle of the 20th century, the increasing shortage of energy, the increasingly stringent environmental protection laws and regulations, and the gradual rise of labor costs, copper smelting technology has developed rapidly since the 1980s. Forcing the traditional methods to be replaced by new strengthening methods, the traditional smelting methods have been gradually eliminated. With the rise of advanced technology represented by flash smelting and molten pool smelting, the most important breakthrough is the wide application of oxygen or rich oxygen. After decades of efforts, flash smelting and molten pool smelting have basically replaced the traditional hot smelting process.

1. Fire smelting process

The fire process mainly includes four main steps: matte smelting, matte (matte) blowing, crude copper fire refining and anode copper electrolytic refining.

Sulfur smelting (copper concentrate-matte): mainly using copper concentrate to make matte smelting, the purpose is to oxidize part of the copper concentrate iron, slag removal, the production of higher copper matte.

Matte blowing (matte-crude copper): further oxidation of matte, slag removal of iron and sulfur from matte to produce crude copper.

Fire refining (crude copper-anode copper): crude copper is further removed by oxidation slagging to produce anode copper.

Electrolytic refining (anode copper-cathode copper): through the introduction of direct current, anodic copper dissolution, precipitation of pure copper in the cathode, impurities into the anode mud or electrolyte, so as to separate copper from impurities and produce cathode copper.

General flow chart of copper smelting by fire

2. Classification of pyro-smelting process

(1) Flash smelting

Flash smelting (flash smelting) includes Inco (Inco) flash furnace, Otto Kunpu (Outokumpu) flash furnace and vortex top blowing smelting (ConTop). Flash smelting is a smelting method to make full use of the huge active surface of fine grinding materials to strengthen the smelting reaction process. After the concentrate is deeply dried, the concentrate is sprayed into the reaction tower with oxygen-enriched air together with the flux, the concentrate particles are suspended in space for 1 to 3 seconds, and the oxidation reaction of sulphide minerals occurs rapidly with the high temperature oxidizing airflow, and a large amount of heat is released. The process of smelting reaction, that is, matte formation, is completed. The reaction products fall into the sedimentation tank of the flash furnace and precipitate, so that the copper matte and slag can be further separated. This method is mainly used for matte smelting of copper, nickel and other sulphide ores.

Flash smelting began production in the late 1950s and has been widely used in more than 40 enterprises, because continuous improvement has made remarkable achievements in energy saving and environmental protection. The technology has the advantages of large production capacity, low energy consumption and less pollution. The maximum copper production capacity of a single system can reach more than 400000 t / a, which is suitable for factories with a scale of more than 200000 t / a. However, the raw material is required to be deeply dried to less than 0.3% water, the particle size of concentrate is less than 1mm, and the impurity lead and zinc in the raw material should not be higher than 6%. The disadvantage of the process is that the equipment is complex, the smoke and dust rate is high, and the copper content in slag is relatively high, so it is necessary to carry out dilution treatment.

The most competitive, fastest developing and widely used in flash smelting is Otto Kunpu flash smelting. The amount of copper produced by this method accounts for more than 1/3 of the world copper output. Flash smelting has the advantages of mature and reliable technology, high degree of automation, high production intensity, low operating cost and good environmental protection, so it is called the standard clean copper smelting process.

Otto Kunpu Flash Furnace: this technology is the most advanced copper smelting technology in the world, with the characteristics of energy saving, environmental protection and high efficiency. And through the computer on-line optimization control system to carry on the "double flash" copper smelting technology, is in the leading position in the world copper smelting range. Due to the increasingly stringent environmental requirements, the P / S converter in the old smelter is becoming obsolete and can not meet the environmental requirements. From the point of view of heat balance and slagging, the grade of matte melted by P-S converter is very difficult to exceed 65%, and since flash blowing can be used with high concentration and rich oxygen, the heat balance can be guaranteed. Therefore, the grade of matte produced by flash smelting can reach or even exceed 70%, which makes the smelting efficiency very high, which is in line with the development trend of copper flash smelting "four high"-high feeding, high grade, high oxygen concentration and high heat negative technology.

Flash smelting process flow chart

(2) molten pool smelting

Molten pool smelting includes Tennant copper smelting process, Sanding process, Osmat process, Vanukov copper smelting process, Aissah smelting process, Nolanda process, top blowing rotary furnace process (TBRC), silver copper smelting process, Shuikoushan copper smelting process and Dongying bottom blowing oxygen-rich melting method and so on. The molten pool smelting is that when the fine sulphide concentrate is added to the melt, air or industrial oxygen is poured into the melt and intensified melting is carried out in the molten pool with severe stirring. Because the bubble is pressed into the solution pool by the blast, when the bubble rises through the molten pool, it causes the "molten column" to move, thus inputting a great function to the melt. Its furnace type is horizontal, vertical, rotary or fixed, and there are three ways of blowing: side blowing, top blowing and bottom blowing.

Molten pool smelting began to be used in industry in the 1970s. Because of the good effect of heat and mass transfer in the molten pool smelting process, the metallurgical process can be greatly strengthened, and the equipment productivity can be improved and the energy consumption in the smelting process can be reduced. Moreover, the requirements for furnace charge are not high, all kinds of concentrate, dry, wet, large particle, powder are suitable, the furnace volume is small, the heat loss is small, energy saving and environmental protection are relatively good, especially the smoke and dust rate is obviously lower than that of flash smelting.

Osmat process: Osmett top blow immersion spray qiang process has been widely used in the commercial production of non-ferrous metals and precious metals as well as high temperature treatment of various wastes. At the end of 2003, 16 smelters around the world, including Osmett's new demonstration plant in South Australia, used the Osmett process for commercial production. These include the Jinchang smelter in Tongling, China, the copper plant in India and the recycled copper factory of the Korean Zinc Company. Osmat plants can be equipped with single or multiple furnaces and usually do not require complex material and flue gas treatment systems. Due to the simplicity, flexibility and high energy efficiency of the process, the cost of equipment using the Osmat process is relatively low. The Osmat process focuses on reducing the size and complexity of peripherals, so low-cost modifications in or around the Osmat furnace system enable customers to reduce the scale of tail gas treatment. In particular, sulfur fixation and acid plants, fuel and gas delivery systems. The raw material is simple and the feed does not require drying and grinding.

The main smelters of copper smelting capacity in the world in 2011

Comparison of main Copper smelting processes

Rough refining capacity of major domestic copper enterprises (as of 2013)

Smelting process of some Foreign Copper Enterprises

It should be noted that recycled copper smelting is also a kind of pyro-smelting. Copper itself is a renewable resource, and recycled copper is an important raw material for copper smelting. According to the (ICSG) data of the International Copper Research Organization, in major developed countries, The proportion of recycled copper production is very high, of which the United States accounts for about 60%, Japan about 45%, Germany about 80%.

1. Smelting process of recycled copper

The treatment process of recycled copper depends on the raw materials. About 2 to 3 of the high grade copper waste is directly used in the production of copper products without smelting treatment, and 1 to 3 of the waste miscellaneous copper needs to be melted and treated. At present, there are many methods for the recovery and utilization of scrap copper at home and abroad, which can be divided into two categories: the first is to smelt high quality scrap copper directly into purple copper or copper alloy for use by users, which is called direct utilization; The second type is the smelting of waste miscellaneous copper into anode plate and then electrolytic refining into electrolytic copper for use by users, which is called indirect utilization. Among them, the second kind of method is divided into high-grade and low-grade according to raw materials, and the smelting process is divided into one-stage, two-stage and three-stage smelting process.

One-stage method: copper grade > 98% copper, brass, electrolytic residual electrode, etc., directly added to the refining furnace to refine into the anode, and then electrolyzed to produce cathode copper.

Two-stage process: waste miscellaneous copper is melted in the smelting furnace, blown into crude copper, and then refined by refining furnace-electrolytic refining to produce cathode copper.

Three-stage process: waste miscellaneous copper and copper-containing waste through blast furnace (or ISA furnace, TBRC furnace, Cardo furnace, etc.) smelting-converter blowing-anode refining-electrolysis to produce cathode copper. The raw material grade can be as low as 1% copper.

The three-stage method has the advantages of high comprehensive utilization of raw materials, simple and easy treatment of smoke and dust, high grade of crude copper, easy operation of refining furnace, high equipment productivity and so on. However, it has some shortcomings, such as complex process, many equipment, large investment and high fuel consumption. Therefore, the smelting process of recycled copper generally adopts the combination of two-stage process and three-stage process, which is beneficial to reduce energy consumption and improve the comprehensive recovery and utilization of valuable metals.

II. Introduction of main smelting processes

1. (KRS) of Caesar recovery and Recycling system in North German Refining Caesar smelter

The North German Refining Caesar smelter is the largest and most advanced recycled copper refinery in the world. Caesar smelter replaced three blast furnaces and one PS converter with one ISA furnace to deal with the residue and miscellaneous copper containing 1% and 80% copper. ISA furnace intermittent smelting and blowing, containing copper residue and miscellaneous copper, first reduced smelting in ISA furnace to produce black copper and silicate slag, black copper continued blowing to produce 95% crude copper.

2. Blast furnace-converter-reflector process in MontanwerkeBrixlegg smelter, Austria

The Montanwerke Brixlegg smelter is the only copper smelter in Austria with scrap copper containing 15% to 99% copper. The production process is composed of blast furnace, PS converter, fixed anode furnace and electrolysis, which is a typical three-stage method.

The characteristics of this process are as follows: different grades of residue and copper with different technological processes to produce different products. The residue raw material containing 15% and 70% copper is produced by advanced blast furnace, black copper is reduced by coke, crude copper is produced by converter, black copper and copper alloy containing more than 75% copper are directly entered into converter, crude copper containing more than 96% copper is refined in anode furnace. The miscellaneous copper and crude copper with higher copper grade are refined directly into the anode furnace, while the bright copper with higher copper grade does not need smelting treatment and is directly added to the induction furnace to produce copper, which has strong adaptability to raw materials.

3. (TBRC) smelting process of oxygen top blowing rotary converter in Metallo-Chimique smelter, Belgium

The TBRC furnace of Metallo-Chimique smelter has strong adaptability to raw materials, and the raw materials treated are very mixed and there are many kinds of raw materials. The main raw materials are industrial residues containing 25% to 30% copper, various copper alloys (brass, bronze, etc.), waste motors, sponge copper, cables, miscellaneous copper of various grades, etc. It is especially used to deal with low-grade industrial residues containing copper, lead and tin, copper alloys and refractory miscellaneous copper.

4. Caldor furnace for treatment of low grade waste copper

5. NGL furnace refining waste copper process

In view of the shortcomings of the existing waste miscellaneous copper treatment technology, China Ruilin Engineering Technology Co., Ltd. has developed the "NGL" furnace waste miscellaneous copper fire refining process.

NGL furnace is developed by combining the advantages of tilting furnace and rotary anode furnace. There are large feeding door and slag door on the side, oxidation reduction port and breathable brick on the other side, and the furnace body can be rotated at a certain angle. The nitrogen agitation technology is used in the waste copper refining process for the first time in "NGL furnace refining waste miscellaneous copper complete set process and equipment", which effectively strengthens the mass transfer and heat transfer in the refining process and improves the production efficiency. In this process, oxygen entrainment combustion is used for heating, which greatly improves the thermal efficiency, shortens the production cycle, and reduces the amount of smoke discharged by more than 65%.

The complete process and equipment of NGL furnace refining waste miscellaneous copper began in 2010, and large-scale industrial applications were carried out in Shandong Jinsheng Group East Copper Co., Ltd and Guangxi Nonferrous Group Recycling Metal Co., Ltd., respectively. Its four 250t NGL furnace systems were put into production in 2012.

II. Wet smelting (SX-EW process)

Wet smelting accounts for 10% to 20% of copper production, which is a method of leaching copper ore or copper concentrate into solution by solvent, and then recovering copper from purified copper-containing solution. It is mainly used for the treatment of low-grade copper ores, copper oxide ores and some complex copper ores.

The equipment of wet copper smelting is simpler, it is produced near the mine, the production cost is low, the sulfuric acid is not produced, and there is no SO2 pollution. However, the impurity content is high, and the copper smelting period is long, the efficiency is low, the production capacity is small; the recovery of precious metals is difficult and the recovery rate is uncertain; the wet process for the treatment of chalcopyrite concentrate has no industrial application and there are technical obstacles.

Although copper hydrometallurgy accounts for a small proportion in copper production at present, according to the development trend of resources in the future, with the gradual dilution of ores, the utilization of oxidized ores, low-grade refractory ores and polymetallic complex copper deposits is increasing day by day. Wet copper smelting will be an effective way to deal with these raw materials.

1. Wet smelting process

The wet smelting process mainly consists of four steps: leaching, extraction, back extraction, metal preparation (electrodeposition or replacement). Oxidized ore can be leached directly, low grade oxidized ore can be leached by heap leaching, and Cao leaching can be used for rich ore. In general, sulphide ore needs to be roasted before leaching, or it can be leached directly under high pressure. The commonly used solvents in the leaching process are sulfuric acid, an, high iron sulfate solution and so on.

General flow chart of wet smelting

2. Comparison between hot smelting process and wet smelting process.

Comparison of Pyrometallurgical and Wet smelting processes

III. Prospect of copper smelting methods

The development trend of copper smelting in the world the development trend of copper smelting is summarized as follows:

The main results are as follows: (1) because of the nature of copper ore, in order to recover silver and sulfur, fire copper smelting still occupies the main position, but the proportion of wet copper smelting will be increased.

(2) the copper plant will be pollution-free, the emission concentration of sulfur dioxide will be below 300ppm, and the actual yield of sulfur will reach 95% to 99%. No waste water and waste residue discharge.

(3) the smelting of copper by fire will be basically self-heating.

(4) continuous blowing of copper matte will be more widely used.

(5) low grade ores will be utilized by hydrometallurgy. The leaching and extraction efficiency will be further improved in wet smelting.

(6) computer on-line control will be the main means of production control.

(7) the scale of the plant will be larger, each process will be a single furnace production, and the operation will be even less.

With the harshness of environmental protection policies and the increase of production costs, small smelters with high costs and backward technology will be closed one after another, and large and medium-sized smelters will further expand their production scale and reduce costs. Through technical upgrading and transformation, to further improve the utilization rate of raw materials and maximize the recovery of valuable elements in waste slag, waste water and waste gas in the smelting process will be the most important means to reduce the cost.

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