What Is a Copper Anode?

Anode copper is commonly known as "copper copper". It is a copper intermediate product smelted with copper concentrate as a raw material, and generally has a copper content of 98% to 99%. It is a raw material for producing cathode copper by electrolytic method.

There are two ways to use waste mixed copper: one is to produce electrolytic copper after smelting; the other is to directly use, that is, directly use the sorted waste mixed copper to produce copper or alloy products. Focus on the smelting process.

Recycled copper (copper and copper alloy artwork has lost its original value due to wear, cracks or disposal, etc. In this case, they can be remelted to recover copper) The technical route of smelting production mainly includes the following processes:

Raw material pretreatment: According to different raw materials, there are mainly sorting and dismantling of waste equipment.

Fire smelting: The waste copper is smelted into coarse copper and anode copper by the fire method, and then electrolytically refined into cathode copper. Depending on the composition of the waste, three processes can be used: one-stage method, two-stage method and three-stage method.

Electrolysis: Anode copper is produced by electrolytic refining.

Anode copper is commonly known as "copper copper". It is a copper intermediate product smelted with copper concentrate as a raw material, generally containing 98% to 99% copper. It is a raw material for the production of cathode copper by electrolytic method. Crude copper is smelted to form recycled copper.

There are about 100 anode copper smelters in the world, with a production capacity of about 10 million tons, and the import and export trade of anode copper in the world is about 2 million tons. China is an important anode copper importer in the world. ^[1]

The anode copper is electrolytically refined to produce high-purity copper required by the electrical industry, and the precious metals and by-products nickel, bismuth, selenium and tellurium contained in the anode are recovered. Almost 75% of world silver production is a by-product of copper and lead refining, and many precious metals are recovered from ores with very low precious metal content.

The raw material for electrolytic refining is crude copper. Crude copper is refined by fire to remove most of the sulfur and oxygen, as well as a small amount of the heaviest metals. According to the actual operation conditions, the fire refined copper was cast into anodes weighing 159 to 270 kg and 70 x 40 x 7.5 cm to 90 x 90 x 3.75 cm. The anode contains about 99.4% copper and the total amount of impurities is about 0.6%.

The cathode starting sheet for electrolytic production is a pure copper flake that is produced by seeding in a seed tank with a specially polished and oiled seed plate. It weighs 3.64 to 5.91 kg and has a thickness of 1.56 mm. The length and width of the cathode are 2.5 to 5 cm larger than the anode.

The most common electrolytic cell is made of concrete and lined with lead, asphalt, resin or plastic to prevent electrolyte corrosion.

The size of the electrolytic cell is 3.39 × 1.07 × 1.14 meters, which is equipped with a support for the anode and the cathode, which can hold 38 anodes and 39 cathodes. A group of 38 anodes and a group of 39 cathodes. The anode and the cathode are discharged at a predetermined distance. The center distance of the anode is 8.75 to 3.75 cm. One cathode is placed in the center between each two anodes. A cathode is placed at each end of the anode support. Each anode supplies copper ions to the two cathodes. After 14 days of electrolysis, the cathode is 1.25 cm thick and weighs 113.6 kg when the cathode is removed. After 28 days of electrolysis, the weight of the anode was reduced to 8-15% of the original weight. Remove the residual electrode, wash it, and then return to the anode furnace to remelt it and cast it into a new anode.

Theoretically, the electrolyte contains

40 g / l,

200 g / l, it is only used as a reaction medium, the copper ion concentration in the solution does not change. However, in production, the concentration of copper ions will increase. Generally, several decanting tanks are used in the electrolytic system. Excess copper ions are precipitated with insoluble lead anode and copper cathode to maintain the copper ion concentration in the electrolyte at the required level. . The circulation of the electrolyte is also necessary. The electrolyte is usually added from the bottom of the electrolytic cell and flows out from the upper part of the electrolytic cell to achieve circulation. This cycle reduces the tendency of the electrolyte to delaminate, because the anode copper enters the electrolyte, the electrolyte is saturated with the specific gravity copper sulfate, and the copper sulfate will sink downward. At the same time, copper is precipitated from the solution on the cathode, leaving a dilute sulfuric acid solution with a small specific gravity, which will rise. Therefore, continuous mixing should be avoided to prevent the electrolyte from delaminating and seriously hinder the smooth progress of production.

In order to prevent the accumulation of major impurities such as nickel and arsenic in the electrolyte from exceeding the allowable limit, sufficient electrolyte must be regularly extracted for purification, because soluble impurities in the electrolyte directly affect the purity of the cathode product. Generally, three electrolytic cells connected in series are used to purify the electrolyte. The purification tank adopts lead anode and copper cathode. The first tank produces good-quality cathode copper, the second tank produces copper with a lower pressure and is sent to the anode furnace for melting. The third tank produces low-grade deposits containing high arsenic and returns to the smelting plant.

The copper removal solution is mainly composed of nickel sulfate and sulfuric acid, and is concentrated in a lead evaporator for 6 to 7 hours until the sulfuric acid concentration reaches 1000 g / l. During cooling, nickel was precipitated as anhydrous crude nickel sulfate and removed by filtration. The purified acid solution is returned to the electrolytic plant.

The electrolytic cells generally used for copper electrolytic refining are arranged by the complex method. The anode spacing is small to keep the cell voltage to a minimum, and the average cell voltage is 0.25 volts. The cathode current density is 177.6 222A / m2, and the current efficiency is more than 90%. The current intensity complies with Faraday's law, so 100% current efficiency, 1.186 grams of copper can be deposited in 1 amp hour (copper is a divalent mutual).

The circulating electrolyte is heated to 60 ° C in a steam heating pool, and then lifted to a high-level tank by a pump, and the high-level tank circulates by itself to each electrolytic tank at a flow rate of 9 to 18 liters / minute. The circulating electrolyte is drawn from the upper part of the electrolytic cell, and new electrolyte is added to the bottom of the electrolytic cell. The anode sludge sedimentation is opposite to the flow direction of the electrolyte. In addition to heating to improve the efficiency of the electrolytic cell, a small amount of glue and salt need to be added. Adding glue can improve the quality of the copper cathode, and the added amount is usually 45.5 g / ton cathode copper. When the chloride concentration is maintained at 0.012 ~ 0.03 g / L, silver, bismuth or antimony in the solution can be precipitated.

Cathode copper can be cut directly for sale, used to make alloys, or melted in DC electric arc furnaces or reverberatory furnaces and cast into wire rods, ingots, billets or slabs that meet the requirements for sale. It is best to use an electric furnace, because unlike the reflection furnace, fuel combustion pollution does not require blowing, wood insertion reduction, and no slagging to remove this pollutant. There is a charcoal coating in the inclined furnace next to the melting furnace to prevent oxidation. With

99.98% of refined copper is cast into the mold of a horizontally rotating circular ingot casting machine. If required, copper with 0.03% oxygen can also be obtained, that is, during the smelting and ingot phase, air is blown into the melt to achieve

0.9%, and then reduce the oxygen content of the melt to 0.03% by cutting wood. ^[3]