SMM7 March 17: at the current Copper Summit in SMM, Huang Chongqi, academician of the Chinese Academy of Engineering, explained the domestic scrap copper direct recycling rod technology, production line, product standard, quality evaluation system, industrial chain related supporting and new progress, in order to achieve the expected industrial production and standardize market operation, high quality, high price and smooth material road.

China is short of copper, and China is also a big copper user. At present, the copper consumption of China's cable industry is about 7.5 million tons, accounting for more than 60% of China's total copper consumption, accounting for about 1 percent of the world's total copper conductor consumption, making it the largest copper user in the world.

In order to solve the serious national quality problem of waste copper regeneration rod, improve the energy saving and environmental protection effect of waste copper regeneration rod production, eliminate the old technology and equipment of waste copper regeneration rod production, and adopt domestic new technology and equipment, realize the upgrading of waste copper recycling rod production. With the support of the science and technology support project of the Ministry of Science and Technology of China, after years of efforts, the manufacturing technology (FRHC), which is used by electricians to directly regenerate high conductive copper rods by fire refining of scrap copper, has achieved results.

The pretreatment of waste enamelled wire has made new achievements and has entered the stage of industrialization.

The national standards for recycled copper raw materials and recycled brass raw materials have been promulgated in 2019.

The standard (YS) for smelting recycled copper (FRHC) wire billet and the energy standard (NB) for high conductivity copper (FRHC) rod refined by fire method have been promulgated and implemented. These new standards will play a leading role in improving product quality, standardizing the market and green environmental protection.

Abroad, the European standard (copper and copper alloy rods for drawing wires) and the American standard (copper rods for electrical engineering) listed FRHC rods in the national standards as early as 2013 and 2015 respectively.

In order to implement the general policy of "sustainable development", save copper resources, promote energy conservation, environmental protection, technological upgrading, eliminate backward processes and improve quality, we need to develop advanced technology and high-end equipment.

(FRHC) production line for direct regeneration of continuous casting and rolling rod by pyrometallurgical refining of scrap copper for electrical engineering

The technological process of Direct Regeneration of scrap Copper by Fire Refining

New equipment-Innovation of 120000 t / a scrap Copper Fire Refining Direct Regeneration continuous casting and Rolling Rod production Line

Copper is the first high-end equipment production line in China, which is not only suitable for direct regeneration of scrap copper to produce electrical copper rods, but also suitable for the production of electrical copper rods with electrolytic copper.

The production line integrates the latest technology, equipment, auxiliary facilities and automatic control at home and abroad.

For the first time in several decades, automatic liquid level control of continuous casting has been realized in China, thus reducing labor intensity, stabilizing product quality and filling in the domestic blank.

The production line realizes real-time and on-line quality control, ensures the consistency of stable production and product quality, and improves the "rollability, drawability and annealing" of the products.

Advanced and efficient gas purification technology and combustion system are adopted to realize PLC interface control, which has the remarkable characteristics of enhanced smelting, efficient impurity removal, green environmental protection and low energy consumption. according to the difference of raw materials, the natural gas consumption index is about 75-95m3/t copper rod, which is about half of the energy consumption compared with the traditional scrap copper-anode copper-electrolytic copper-reverberatory furnace smelting-old domestic continuous casting and rolling production line. The rate of finished products is almost 100%.

The new type of two-high cantilever continuous rolling mill is integrated and innovated, the stand is driven separately, the rolling pass is adjusted quickly and accurately, the elongation of the whole rolling system is adjustable, the roll can be changed and adjusted quickly, and the difficult problem of mixing oil and milk in our country for decades has been completely solved. prolong the service life of the rolling mill roll, reduce the production cost and improve the production efficiency;

Accurate temperature control and oxygen control are realized, and the product quality is stabilized.

It solves the automatic control of the flow rate, temperature and pressure of the auxiliary system liquid (cooling water, emulsion, lubricating oil, cleaning fluid) and emulsion filtration, which makes the auxiliary machine cooperate with the main engine and ensures the stable production.

By using the current international advanced control system, a series of functions such as chain start and stop of equipment, automatic adjustment of loop, alarm and recording are realized, and the compatibility, reliability and response speed of the system are effectively guaranteed.

Industry standard and quality evaluation system

The industry standard and quality evaluation system of wire and cable are established for the first time in China, which creates conditions for energy saving and environmental protection, making the best use of materials, high quality and high price.

The scrap copper direct rod smelting standard "Electrical Fire Refining recycled Copper Wire Billet" (YS/T 793 Mel 2012) has been formally implemented since November 1, 2012, and the YS smelting standard has filled the domestic gap in the industry.

The Special Standard for Electrical Fire Refining of High Conductive Copper Rod Wire and Cable Industry was drafted, and the indexes of copper content, copper powder content, oxide film thickness and spiral elongation of recycled copper rod were specified for the first time in China, and the corresponding test methods and equipment were developed, which created conditions for ensuring the mechanical and electrical properties and processing performance of the products. In addition, the oriented application suggestions for three kinds of copper rod grades are put forward, which creates conditions for making the best use of materials, high quality and high price.

Establish the quality evaluation system of recycled copper rod. The formation of a three-combination evaluation system of production process, product performance and product application can effectively comprehensively evaluate the quality level of domestic recycled copper rod and promote the improvement of product quality and industry technical level of recycled copper rod.

This quality evaluation system is also applicable to the evaluation of the quality of electrolytic copper and its rising water.

The domestic demonstration production line of 120000 t / a scrap copper direct regeneration rod by fire refining has introduced, digested and absorbed the most advanced relevant technology and equipment in the world, and the scientific research achievements obtained by the research group have been integrated into the production line in time. The integration and re-innovation and redesign of a brand-new production line have been realized, so that the imported production line has been upgraded and a high-end demonstration production line has been formed. As a result, the product quality and the "three properties" of the process are steadily improved, creating conditions for popularization and application.

The advanced nature of the upgraded demonstration production line is mainly reflected in:

The pre-furnace pretreatment equipment of raw material has been independently developed, and the classification and management system of scrap copper raw materials has been established.

Under the condition of complex and continuous production of waste copper impurities, a new process of rapid impurity removal has been improved and realized.

The furnace group of the continuous production line has been upgraded and reformed, and scrap copper with copper content of 96% or more is successfully used, and stable electrical copper water can be continuously supplied through shaft furnace, refining furnace and holding furnace. it has become a reality for the first time in China to use low-grade scrap copper in the continuous furnace production line.

The research and selection can meet the domestic refractories of each furnace group, greatly increase the service life of refractories (about 30%), reduce the cost by about 30%, and reduce the entry of non-metallic inclusions into copper water and affect product quality.

The domestic newly designed production line realizes the automatic control of continuous casting liquid level (which is the first in China) and the linkage control of metallurgical furnace group, which ensures the stability of casting strip quality and improves the quality of copper rod.

The on-line monitoring system of copper rod quality is improved, which makes the copper rod quality more intuitive and real-time monitoring, convenient for employees to deal with in time, and more controllable.

The newly designed domestic production line adopts a continuous rolling mill with five-wheel continuous casting and two-roll stand and its whole auxiliary system, which realizes the automatic and intelligent operation of the matching of main and auxiliary machines in the whole production line, and creates conditions for stabilizing the quality of copper rod.

On-line continuous cleaning, waxing, eddy current and magnetic joint flaw detection of copper rod are realized. The surface finish and quality of the copper rod are guaranteed.

The bar winding machine system is improved, and the tight binding and on-line packaging are realized, and the safety is good.

For scrap copper with copper content greater than or equal to 96%, the product quality of the copper rod produced by fire refining, continuous casting and rolling is tested by the National Wire and Cable testing Center, the principal component (copper + silver) ≥ 99.90%; electrical conductivity ≥ 100.5% IACS; oxygen content ≤ 400ppm; elongation ≥ 38%; fully meet the requirements of national and industry (GB, NB, YS) standards; The best electromechanical performance indexes, such as torsion, elongation, copper powder content and oxygen content, can be comparable with the electrolytic copper rod made of T1, and the overall electromechanical performance level is between T1 and T2 of the national standard copper rod.

Application trend

The recycling industry is a sunny industry with great prospects, but our country starts late and the overall level is low. We must proceed from the whole, pay close attention to the perfection and matching of the industrial chain, build a new domestic production line, according to the new national standard of recycled copper raw materials, strengthen the pretreatment of raw materials, control the chemical composition, implement the new national standard for making rods, improve the performance of recycled copper rods, stabilize product quality, save energy, and meet the requirements of green environmental protection.

In order to absorb historical lessons, adopt existing scientific and technological achievements, and expand application, we still need to do solid and in-depth improvement and matching work of the entire industrial chain, in order to achieve the goals of high-quality industrial production, standardizing market operation, smooth flow of materials, and high quality and high price; to prevent market chaos and abuse, supervise production and environmental protection indicators, and standardize manufacturing technology and equipment, testing and products. To this end, it is necessary to establish a quality assurance system with high quality and stability as the center and the whole industrial chain.

In order to expand the application, the most important thing to be paid attention to at present involves the following aspects:

(1) to raise the threshold for entry into the recycling industry;

(2) to legislate and establish a recycling system of scrap copper to ensure the smooth flow of wood roads;

(3) the new pretreatment technology and equipment of scrap copper should be developed to make the best use of scrap copper and improve the technical and economic benefits.

(4) as a model, FRHC copper rod is included in our national standard (GB), which is in line with the international advanced standard, and it is also convenient for users to choose.

Expanding the application of directly regenerated copper in fire refining

Fire refining directly recycled copper (FRHC) is not only used in electrical copper rods and wires, but also can be used in other products (general performance requirements are lower than electrical grade products). In the European Standard for Copper and Copper Alloy rods for Wire drawing (BS EN1977:2013), (FRHC) for directly recycled copper rods with high conductivity by fire refining has been included as a grade in the European standard, as is the 2015 ASTMB49-15a standard in the United States.

According to the different requirements for copper grade of copper and copper alloy products, the direct recycled copper can be widely used in the following situations:

(1) Electrical grade FRHC copper rods, copper wires and profiles;

(2) ordinary copper bar;

(3) ordinary copper tube;

(4) ordinary copper strips and profiles;

(5) ordinary copper plate;

(6) phosphorus copper balls for circuit board electroplating, etc.

New Progress in Pretreatment of FRHC Copper Rod production

"Pyrolysis and melting" pretreatment method

De-lacquer on waste enamelled wire, tin or tin-lead alloy on waste copper wire and dealumination on copper-clad aluminum wire, the application of "pyrolysis melting" technology in pretreatment is a new technology of independent innovation in our country, and has realized industrialization and practical application.

Principle: "Pyrolysis", also known as dry distillation, is a basic thermochemical process in which organic matter is heated in isolation of air or partially burned in the presence of a small amount of oxygen to convert it into useful fuel or chemical raw materials. "melting out" means that all kinds of substances separate the liquid phase from the solid phase in the melting state or in the process of slow cooling due to different melting points.

Technical highlights:

(1) Environmental protection is guaranteed-the oil and gas produced by pyrolysis is discharged in a closed system (anoxic or reductive atmosphere does not contain synthetic dioxins), and the pyrolytic oil and gas is burned at a high temperature of 800C-900C after condensation separation and purification. The existence of dioxins is effectively eliminated (dioxins are completely decomposed and burned at 1000 ℃ for 26 seconds, and completely decomposed and burned at 1000 ℃ for 1 second.

(2) Energy saving-the continuous production line of pyrolysis and melting is 60% more energy-saving than the discontinuous pyrolysis furnace; the oil and gas from continuous pyrolysis can be recycled in environmental protection, and there are at least 30 kilograms of pyrolysis oil and gas per ton of waste enamelled wire, which can be used as the fuel produced by ourselves. as a result, energy saving can be realized to the maximum extent.

(3) the resources can be fully utilized-the oxidation loss of copper can be avoided, the metal recovery rate is more than 98%, copper and activated carbon can be well separated, and activated carbon can also be recycled.

Alkaline stripping of waste enamelled wire

Pretreatment stage-including: enamelled wire breaking, magnetic separation, cyclone dedusting, colored sorting, basket loading, etc.

Insulation layer depolymerization stage-including: soaking, heating, etc., NaOH concentration 20% Mel 30%, paint peel temperature 80 Mel 90 ℃, 2 hours, paint layer residual rate 4.17% Mel 4.87%.

In the post-treatment stage, including alkali washing, rinsing, packing, etc., the pilot production line with this method has an annual production capacity of 10,000 tons.

New Progress in Standardization

The new versions of the standards of GB/T38471-2019 "recycled Copper Raw Materials" and NB/T10194-2019 "Electrical Fire Refining of High Conductive Copper rods" have been promulgated and implemented.

The current YS/T793-2012 "Electrical Fire Refining of recycled Copper Wire Blank", the European Standard EN1977:2013 "Copper and Copper Alloy rods for Wire drawing" and American Standard ASTMB49-15a (2015)

The European Union and the United States have listed FRHC copper bars in the national standards in 2013 and 2015 respectively. Compared with the above standards, the new version of the standard in China has the following characteristics.

GB/T38471-2019 standard

The requirements for recycled copper raw materials have been improved, which is conducive to targeted material selection for downstream products and to stabilize the quality of products.

It is beneficial to reduce the cost of downstream products and improve technical and economic benefits.

It is beneficial to reduce and control pollution in the production of downstream products.

Characteristics of NB/T38471-2019 Standard

The raw materials are regulated, and the average copper content in the furnace is required to be more than 96%.

The content of "Cu+Ag" is stipulated, and it is required that the copper content of the copper rod is not lower than 99.9%, otherwise the electrical conductivity of the downstream products will not be stable to meet the requirements of 100%IACS.

The copper pole is classified into three grades: TZ1, TZ2 and TZ3.

The amount of copper powder, oxide film thickness and annealability are defined as mandatory indexes, and the test methods for oxide film thickness and annealability are established.

According to the category of wire and cable products, the recommendation for the use of FRHC copper pole grade has been added.

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