Pyrometallurgical copper smelting is to make blister copper with more than 18% copper concentrate powder and solvent at high temperature, or first smelt copper concentrate powder into matte (copper, iron, sulfur-based melt) and then smelt it into blister copper. Except for some preparatory operations and electrolytic refining operations, The biggest advantage of the process is that it has wide adaptability and can handle various copper ores, especially for general sulfide ores and rich oxide ores.

This  process is carried out at high temperature.

This process , while Compared with  the  fire method and wet method, is carried out at high temperature.

there are the following characteristics:

(1) The hydro-smelting equipment is simpler, but the impurity content is higher, which is a beneficial supplement to the pyro-smelting.

(2) Pyrometallurgy has limitations, subject to the grade and type of ore.

(3) The cost of pyrometallurgy is higher than that of wet method.

It can be seen that hydrometallurgy technology has considerable advantages, but its scope of application is limited, and not all copper ore smelting can adopt this kind of technology. However, through technological improvement, more and more countries, including the United States, Chile, Canada, Australia, Mexico and Peru, have applied this process to more copper ore smelting in recent years. The improvement of hydrometallurgy technology and the promotion of its application have reduced the production cost of copper and increased the production capacity of copper mines

Brief description of copper electrolytic refining process

The grade of cathode copper produced by fire refining is generally 99.2~99.7%, which also contains 0.3~0.8% impurities. In order to improve the performance of copper to meet the requirements of various applications and to recover the valuable metals in it, especially precious metals, platinum group metals and scattered metals, it must be electrolytically refined.

Blister copper electrolytic refining uses the copper anode plate as the anode, the pure copper starting plate or stainless steel plate as the cathode, copper sulfate and sulfuric acid solution as the electrolyte, and the plates are arranged in the electrolytic cell according to a certain pole distance. Direct current, the anode is continuously dissolved, and electrolytic copper is deposited on the cathode. During the electrolysis process, precious metals and valuable elements such as selenium and tellurium in the anode copper enter the anode slime, deposit on the bottom of the electrolytic tank, and are discharged regularly, and sent to the anode slime workshop to extract precious metals. Most of the impurities such as nickel, arsenic, antimony and bismuth enter the electrolyte, and a part needs to be extracted from the circulating liquid for purification. The technological process includes two parts: electrolytic refining and electrolyte purification.

The electrolytic refining process has three methods: conventional electrolysis, periodic reverse current electrolysis and permanent cathodic electrolysis.

1. Conventional electrolysis

The pure copper initial electrode is used as the cathode, the power supply is constant direct current, and the current density is 220-280A/m2. This method has many years of production history in all countries in the world, the process is mature and reliable, and the power consumption is low. Especially after adopting a cathode and anode processing unit with high level of mechanization and automation, and adopting new technology to properly improve the verticality of cathode and anode plates, the quality of cathode copper products has been significantly improved

However, the production process of the starter sheet by the traditional method is complicated, not only requires an independent production system, but also requires too much labor intensity in the production process. In addition, there are two insurmountable shortcomings in this process itself: (1) There is a “limiting current density” in the electrolytic refining process, and the actual current density during electrolytic refining must be lower than the limiting current density, otherwise it will The surface of cathode copper deposition is rough, and even “dendrites” are formed, causing a short circuit in the electrolytic cell, greatly increasing the energy consumption of the electrolysis process, and affecting the normal production process and product quality. (2) It is easy to form “anode passivation”, the anode cannot be dissolved under normal voltage, and the voltage must be increased to destroy and dissolve the passivation film at a higher voltage, which not only affects normal production, but also causes waste of electric energy and cathode copper The chemical composition of the product is unstable, which in turn affects the quality and physical properties of the product.

2. Periodic reverse current electrolysis

An electrolytic method in which the direction of a direct current is changed periodically for short periods of time. The cathode and anode of the electrolysis are the same as the conventional electrolysis, and the periodical short-term reverse is to overcome the passivation of the anode, and the current density reaches 300-350A/m2. , can strengthen production, save investment, and shorten the production cycle of electrolytic copper. The disadvantage is that the current efficiency is low, and the power consumption is higher than that of conventional electrolysis. It is suitable for old factories to expand production capacity and to be used in areas with low electricity prices.

3. Permanent cathodic electrolysis

Also known as Isa (ISA) electrolysis. Different from conventional electrolysis, the cathode is a permanent stainless steel plate, and the electrolytic copper deposited on the stainless steel cathode plate is periodically taken out and peeled off as a finished product. In 1979, the Australian Refined Copper Company (Coppei refinet iesply Ltd. CRL) first applied this method to the industrial production of copper electrolytic refining, and later refineries in the United States, Canada and the Federal Republic of Germany also applied this method. Its advantage is that it can save the production system of copper plate, the stainless steel cathode is straight, the occurrence rate of short circuit is low, and the cathode quality is high.

The Layout in below is  ISA electrolytic process.