Introduction: As one of the hardware, the human application of copper has a long history. At present, there are two kinds of smelting methods for producing electrolytic copper in the world: pyrometallurgical smelting and hydrometallurgical smelting. At present, more than 80% of refined copper is produced by pyrometallurgical process, and about 20% is produced by hydrometallurgical process. So what are the new advances in copper smelting technology? This article takes you through an inventory.

Copper is a prehistoric metal, early in the primitive society by human discovery and application. With the appearance of copper, the Stone Age disappeared, and mankind gradually stepped into the Bronze Age.

The invention of copper electrolytic refining in Europe in 1865 is of great significance to the progress of copper smelting technology. It is necessary to mention the history of copper smelting in China. In the Tang and song dynasties, it was mainly concentrated in the lead mountains of Jiangxi, Dexing, Jiangxi and Guangdong, with annual output of up to nearly 2,000 tons. The ancient mines in Tongling are larger and have a long history, and have been the center of copper mining and smelting from the Shang and Zhou Dynasties to the Tang and song dynasties. Until 1949, only Shenyang smelter, Shanghai smelter, Kunming smelter and Chongqing smelter were left in the country with a small output of less than 3,000 tons. After 1949, the overall level of Chinese industry rose rapidly, with the construction of large-scale Copper Smelters in Tongling, silver, Daye and Yunnan.

At present, there are two kinds of smelting methods for producing electrolytic copper in the world: pyrometallurgical smelting and hydrometallurgical smelting. At present, more than 80% of refined copper is produced by pyrometallurgical process, and about 20% is produced by hydrometallurgical process.

1. Fire smelting

Copper smelting by fire is the main method of copper production, accounting for about 80% of copper output, mainly dealing with sulfide ore. The advantages of pyrometallurgical copper smelting are high adaptability of raw materials, low energy consumption, high efficiency and high metal recovery. Pyrometallurgical copper can be divided into two categories: one is the traditional process: such as blast furnace smelting, reverberatory furnace smelting, electric furnace smelting. Second, the modern strengthening process: such as flash furnace melting, melting pool melting.

Since the middle of the 20th century, the global energy and environmental problems have become more and more serious, the environmental protection laws and regulations have become increasingly strict, and the labor cost has gradually increased, which has promoted the rapid development of copper smelting technology since the 1980s, forced the traditional method had to be replaced by the new strengthening method, the traditional smelting method was gradually eliminated. The advanced technology of intensified smelting, represented by flash smelting and bath smelting, is emerging, and the most important breakthrough is the extensive application of oxygen or oxygen-enriched. After decades of efforts, flash smelting and bath smelting have basically replaced the traditional fire smelting process.

(1)pyrometallurgical process flow

The pyrometallurgical process includes four main steps: Matte smelting, Copper Matte (Matte) converting, crude copper pyrometallurgical refining and anode copper electrolytic refining. Sulphur Smelting (copper concentrate-matte) : mainly using copper concentrate matte smelting, the aim is to make copper concentrate partial iron oxidation, slag removal, to produce copper matte with high copper content. Matte blowing (matte-coarse copper) : The further oxidation of Matte, slag removal of iron and Sulfur Matte, the production of coarse copper. Fire refining (crude copper-anode copper) : The crude copper through oxidation slag to further remove impurity elements, the production of anode copper. Electrolytic refining (anode copper-cathode copper) : By introducing direct current, the anode copper dissolves, precipitates the pure copper in the cathode, the impurity enters the anode mud or the electrolyte, thus realizes the separation of the copper and the impurity, produces the cathode copper.

General Flowchart of copper smelting by fire process

(2)Classification of pyrometallurgical process

 FLASH SMELTING INCLUDES INCO FLASH FURNACE,

 OUTOKUMPU FLASH FURNACE AND CONTOP smelting of International Nickel Corporation. FLASH SMELTING IS A smelting method that makes full use of the huge active surface of fine-grained materials to strengthen the smelting reaction process. After the concentrate is deeply dried, it is sprayed into the reaction tower with oxygen-enriched air after the flux is dried, the concentrate particles are suspended in space for 1-3 s time, and the oxidation reaction of sulfide minerals takes place rapidly with the high-temperature oxidation gas stream, and a large amount of heat is released, to complete the smelting reaction, the process of matting. The product of the reaction is settled in the settling tank of the flash furnace, and the copper matte and slag are further separated. This method is mainly used for matte-making smelting of sulfide ores such as copper and nickel.

Flash smelting in the late 1950s began production, has been more than 40 enterprises to promote the application, because of continuous improvement in energy conservation and environmental protection has significant achievements. The process 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 400 KT/A. It is suitable for factories with a scale of more than 200 KT/A. However, it is necessary to dry the raw material to a depth of less than 0.3% water content and less than 1mm concentrate particle size. The impurity of lead and zinc in the raw material should not exceed 6% . The disadvantages of the process are that the equipment is complex, the dust rate is high, the copper content in the slag is high, and it needs to be depleted.

In flash smelting, the most competitive, fastest developing and widely used in industry is Otto Kamp Flash Smelting. The amount of copper produced by this method accounts for more than one third of the world's copper production. Flash smelting has the advantages of reliable technology, high automation, high production intensity, low operation cost and good environmental protection. It is called the standard clean copper smelting process.

OTOKUP FLASH FURNACE: THE TECHNOLOGY IS THE MOST advanced copper smelting technology in the world, with energy-saving, environmental protection and high efficiency. The "double flash" COPPER SMELTING TECHNOLOGY BY Computer on-line optimization control system is in the leading position in the world copper smelting range. In view of the problem of heat balance and slagging, it is difficult to smelt more than 65% grade of matte with P-S converter because the environmental requirements are becoming more and more strict and the P-S converter in the old smelter is out of date and can not meet the environmental requirements, because the high concentration oxygen-rich blowing can be used in flash smelting and the heat balance can be ensured, the grade of matte in flash smelting can reach or even exceed 70% , making the smelting efficiency very high, it is in line with the development trend of "four high" copper flash smelting technology with high feeding, high grade, high oxygen concentration and high negative heat.

Flash process flow diagram

(2) bath smelting includes Teniente process

Mitsubishi Process, ausmelt process, Vanyukov process, Isa Process, noranda process, top blown rotary furnace (TBRC) , Baiyin process, Shuikoushan process and Dongying bottom blown oxygen enrichment process. Molten pool smelting is to add fine sulfide concentrate into the melt at the same time, the melt into the air or industrial oxygen, in the intense agitation of the molten pool for strengthening melting. When the bubble rises through the molten pool, it will cause the "melt column" to move, which will input a great function to the melt. Its furnace type has horizontal, vertical, rotary or fixed, blowing mode has side blowing, top blowing, bottom blowing three kinds. Bath smelting was first applied in industry in the 1970s. Because of the good heat and mass transfer effect in the bath melting process, the metallurgical process can be greatly strengthened and the equipment productivity can be increased and the energy consumption can be reduced. All kinds of concentrate, such as dry, wet, big grain and powder, are suitable. The volume of furnace is small, heat loss is small, energy-saving and environmental protection are better, especially the rate of soot is obviously lower than flash smelting. AUSMELT PROCESS: The ausmelt top blown immersion spray Qiang process has been widely used in the commercial production of Non-ferrous metal and precious metals, as well as in the treatment of various wastes at high temperatures. At the end of 2003,16 smelters worldwide were using the ausmelt process for commercial production, including AUSMELT's new demonstration plant in South Australia, these include the Jinchang smelter in Tongling, the copper plant in India and the copper recycling plant of the Korean Zinc Company. Auschwitz plants can be single or multiple furnace configurations and usually do not require complex material and flue gas handling systems. Because of the simplicity, flexibility and high energy efficiency of the process, the equipment cost of using ausmelt process is relatively low. The OSMAT process focuses on reducing the size and complexity of peripherals, so low-cost retrofitting in and around Osmat systems allows customers to reduce the scale of tail gas treatment, in particular, sulfur fixation and acid plants, fuel and gas delivery systems. The material is simple and does not require drying or grinding.

World's major copper smelters in 2011

Comparison of main copper smelting processes

Crude refining capacity of main copper enterprises in China (up to 2013)

Smelting process of some copper enterprises abroad

It should be noted that copper smelting is also a kind of pyrometallurgical smelting. Copper itself is a renewable resource. Recycled copper is an important raw material for copper smelting. According to the International Copper Research Organization (ICSG) , in major developed countries, the share of recycled copper production is very high, with the US accounting for about 60 per cent, Japan for about 45 per cent and Germany for about 80 per cent.

2.Smelting process of reclaimed copper

About 2/3 of high grade copper scrap is directly used in copper production without smelting treatment, and 1/3 of scrap copper needs smelting treatment. At present, there are many ways to recover and utilize copper scrap at home and abroad, which can be divided into two categories: the first is to directly smelt high quality copper scrap into copper or copper alloy for use by users, which is called direct utilization; The second category is the scrap copper into anode plate after electrolytic refining into electrolytic copper for users to use, known as indirect use. Among them, the second method is divided into high-grade and low-grade according to raw materials, from the smelting process is divided into one-stage, two-stage and three-stage smelting. One-stage method: Copper Grade > 98% of copper, brass, electrolytic residue directly into the refining furnace into anode, electrolytic production of cathode copper. Two-stage method: scrap copper in the melting furnace first, blown into crude copper, and then through the refining furnace-electrolytic refining, the output of cathode copper. Three-stage process: the Cathode Copper is produced by smelting scrap copper and copper-containing wastes in blast furnace (or Isa Furnace, TBRC furnace, kaldor furnace, etc.)-converter blowing-anode refining-electrolysis. The grade of raw material can be as low as 1% copper. The three-stage process has the advantages of high comprehensive utilization rate of raw materials, simple composition of flue dust, easy handling, higher grade of crude copper, easier operation of the refining furnace and higher equipment productivity, however, it has the disadvantages of complex process, large equipment, large investment and high fuel consumption. Therefore, the smelting process of reclaimed copper usually adopts the combination of two-stage method and three-stage method, which is helpful to reduce energy consumption and improve the comprehensive recovery and utilization of valuable metals.

3.Introduction of main smelting process

(1)C?SAR recovery and recycling system (KRS) at Northern Germany refining Kaiser smelter. The North German refining Kaiser smelter is the largest and most advanced copper smelter in the world. 1 Isa Furnace was used to replace 3 blast furnaces and 1 PS converter in Kaiser smelter to treat 1% ~ 80% copper-containing residue and miscellaneous copper, black Copper and silicate slag are produced. Black copper is continuously blown to produce crude copper containing 95% copper.

(2) Montanwerke Brixlegg smelter is the only copper smelter in Austria. The raw material is scrap copper containing 15% ~ 99% copper. The process consists of blast furnace, PS converter, fixed anode furnace and electrolysis. It is a typical three-stage process. The characteristics of the process are: Different grade of residue and red impurity copper are produced by different process flow. Black Copper is produced by coke reduction in an advanced blast furnace containing 15% ~ 70% copper residue, and then crude copper is produced by entering the converter The coarse copper and miscellaneous copper with higher copper grade are refined directly in anode furnace, while the bright copper with higher copper grade is produced directly by induction furnace without smelting treatment.

(3)The TBRC furnace of the oxygen top-blown Rotary Converter (TBRC) smelting process me smelter in Belgium me smelter has a strong adaptability to the raw materials, the raw materials handled are very complex, and there are many varieties. The main raw materials are industrial residues containing 25% ~ 30% copper, various copper alloys (brass, bronze, etc.) , used electric motors, spongy copper, cables, miscellaneous copper of various grades, etc. , in particular, the treatment of copper, lead, tin low-grade industrial residues, copper alloys, difficult to deal with copper-based.

(4) low-grade scrap copper is treated by KALDOR furnace. KALDOR furnace is an advanced smelting technology, which can be used to treat scrap copper containing 15%-99% copper with high metal recovery rate and good environmental benefit, strong adaptability, materials do not need pretreatment, can be directly into the furnace, can control oxidation and reduction atmosphere. The low grade scrap copper can be treated by 

(5)steps: feeding, melting, slag discharging, blowing and copper producing. The crude copper grade can reach 96% . In the reaction process, the iron in waste copper is usually used as reductant and quartz flux is added. KALDOR furnace is an advanced process for the treatment of copper scrap by two-stage process abroad. It has been introduced to large smelters in China, such as Jiangxi Copper Industry. 5. In view of the shortage of the existing waste copper treatment technology in NGL furnace, China Ruilin Engineering Technology Co. , Ltd. Developed "NGL" furnace waste copper pyrometallurgical refining technology. NGL furnace is developed by combining the advantages of tilting furnace and rotary anode furnace. It has a large charging gate and slag gate on one side, a redox port and a permeable brick on the other side, and the furnace body can rotate at a certain angle. For the first time, nitrogen agitation technology was used in NGL furnace to refine scrap copper, which effectively enhanced the mass and heat transfer in the refining process and improved the production efficiency. In this process, oxygen entrainment combustion is used for heat supply, which greatly improves the thermal efficiency, shortens the production cycle and reduces the amount of flue gas discharged by more than 65% . Starting from 2010, NGL furnace has been applied in Shandong Jinsheng Group East Copper Co. , Ltd. and Guangxi Non-ferrous Metals in large-scale industrialization, its 4 sets of 250 tons of NGL furnace system were put into production in 2012. Wet Metallurgy (SX-EW) , which accounts for 10% ~ 20% of copper production, is a method of leaching copper ore or copper concentrate into solution by solvent, and then recovering copper from the purified solution containing copper. Mainly used for processing low-grade copper ore, copper oxide ore and some complex copper ore. Wet Copper smelting equipment is more simple, near the mine production, low production costs, no production of sulfuric acid, SO2 pollution. However, it is difficult to recover precious metals, and the recovery rate is uncertain. The hydrometallurgical process for treating chalcopyrite concentrate has not been applied in industry, and there are technical obstacles. Although the proportion of copper hydrometallurgy in copper production is not large at present, the trend of resources development in the future shows that with the ore gradually depleted, the utilization of oxidized ore, low-grade refractory ore and polymetallic complex copper ore is increasing, hydrometallurgy of copper will be an effective way to treat these raw materials.

The hydrometallurgical process

 includes four steps: leaching, extraction, back extraction and metal preparation (electrowinning or replacement) . The oxidized ore can be leached directly, the low grade oxidized ore can be leached by heap leaching, and the rich ore can be leached by Cao leaching. In general, sulfide ores need to be roasted before leaching, or they can be directly leached under high pressure. The commonly used solvents in leaching process are sulfuric acid, an, ferric sulfate solution and so on.

General flow chart of hydrometallurgy.

 Comparison of pyrometallurgical process and hydrometallurgical 

process pyrometallurgical process and hydrometallurgical process comparison of pyrometallurgical process and hydrometallurgical process copper smelting process prospect of the world copper smelting development trend copper smelting development trend can be summarized as follows: 

(1) due to the nature of copper ore, in order to recover the silver and sulfur, pyrometallurgy is still the main method, but the proportion of hydrometallurgy will be increased.

 (2) the copper plant will be pollution-free, the concentration of sulfur dioxide emissions will be below 300 PPM, and the sulfur recovery will reach 95% ~ 99% . Non-waste water and waste residue discharge. 

(3)Copper smelting by fire will be essentially self-heating. 

(4) continuous converting of Copper Matte will be more widely used. 

(5) the low grade ore will be utilized by hydrometallurgy. The leaching and extraction efficiency in hydrometallurgy will be further improved. 

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

(7) the size of the plant will be larger, each process will be a single furnace production, operation will be more reduced. With the strict environmental protection policy and the increase of production cost, the small smelters with high cost and backward technology will be closed gradually in the world, and the large and medium smelters will further expand the production scale and reduce the cost. The most important way to reduce the cost is to improve the utilization ratio of raw materials and to recover the valuable elements in waste residue, waste water and waste gas. 

Source: Poker investor

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