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When treating miscellaneous copper with the one-stage method, it is usually carried out in a fixed reverberatory furnace, so in fact, what is carried out in the reverberatory furnace is both smelting and refining. The refining principle of mixed copper reverberatory furnace is essentially the same as the fire refining principle of ore copper. However, due to the high impurity content of sub-blister copper (sometimes up to 4%), it has its own unique operating characteristics. When mixed copper is processed in a reverberatory furnace, the entire refining process includes melting, oxidation, reduction, slag removal, casting and other operations. At the heart of the entire operation are oxidation and reduction. The following mainly describes oxidation and reduction. The basic principle of miscellaneous copper oxidation refining is that the affinity of most impurities in copper to oxygen is greater than the affinity of copper to oxygen, and the oxides of most impurities have low solubility in liquid copper. Therefore, when air is blown into the melt, the impurities are oxidized and removed first. However, copper accounts for the majority in the melt, and the amount of impurities is very small. Therefore, during oxidation, copper is oxidized first. 4Cu+O2=2Cu2O The Cu2O produced immediately dissolves in the copper liquid and reacts with the impurities in the copper liquid to oxidize the impurities. +=2+(MeO) where: Indicates the concentration of substances in the copper liquid ； ( ) represents the concentration of substances in the slag phase ； Me is impurity metal. The equilibrium constant for this reaction is: The main body in the copper liquid is metallic copper, and the concentration is very high. Since the amount of impurities is relatively small, although the impurities are oxidized by Cu2O, it can be considered to be basically unchanged (that is, a constant). At the same time, since the solubility of the impurity oxide (MeO) in the copper liquid is very small and can quickly reach saturation, in most cases, when the temperature is constant, it can be considered to be a constant value, so the equilibrium constant of the reaction can be expressed by the following formula: K'= This shows that at a certain temperature (that is, K is a definite constant), the impurity content in the copper liquid is inversely proportional to the Cu2O content. The larger the value, the smaller it is, that is, the fewer unoxidized impurities remaining in the copper liquid, the more complete the refining operation. Practice shows that in order to remove impurities in the copper liquid more quickly and completely, the oxidation process should be strengthened so that the concentration of Cu2O in the copper liquid reaches a saturated state. The solubility of Cu2O in liquid copper increases with increasing temperature: Temperature ℃ 1100 1150 1200 1250 Solubility % 5 8.3 12.4 13.1 When the solubility of Cu2O exceeds the solubility at this temperature, the melt will be divided into two layers. The lower layer is a copper liquid saturated with Cu2O, and the upper layer is a Cu2O phase saturated with copper. This relationship can be clearly seen from the Cu ￠ O system phase diagram. The solubility in the copper liquid increases very little, and the melt stratifies, causing part of the Cu2O to enter the slag layer, and excessive oxidation, which increases the reduction process and consumes more reducing agents. Therefore, in order to avoid excessive oxidation of the copper liquid, the oxidation period is required to be maintained at 1150 ~ 1170 ° C. The behavior of main impurities in the oxidation refining process is briefly described as follows: iron. The affinity of iron for oxygen is much greater than the affinity of copper for oxygen, so iron is easily oxidized and removed by slagging. The iron oxidation reaction proceeds as follows:: Cu2O+Fe=2Cu+FeO According to thermodynamic estimates, iron can be reduced to one hundred thousandth during the refining process. nickel. Nickel is an impurity that is difficult to remove. Nickel and copper can generate a series of solid solutions. Although nickel is oxidized during both the melting period and the oxidation period, it is slow and incomplete, and the NiO generated during the oxidation period is distributed between the copper liquid and the slag. NiO dissolved in the slag can generate NiO · Fe2O3 that is insoluble in the copper liquid but soluble in the slag phase. This part of nickel can be removed. Thermodynamic calculations show that when the copper liquid contains 16% nickel, the nickel can be removed to 0.25%. When the copper liquid contains both nickel, arsenic and antimony, the removal of nickel is more difficult. Because NiO dissolved in liquid copper can combine with Cu, As or Sb to form nickel mica (6Cu2O · 8NiO · 2As2O3 or 6Cu2O · 8NiO · 2Sb2O3) dissolved in liquid copper. In order to remove nickel, only alkaline flux can be added to decompose nickel mica. zinc. Zinc and copper are completely miscible in the liquid state. The boiling point of zinc is 906°C. During refining, most of the zinc volatilizes in the form of metal during the melting stage, and is then oxidized to ZnO by the oxygen in the furnace gas. It is discharged with the furnace gas and collected in the dust collection system. The remaining zinc is oxidized to ZnO in the early stage of oxidation, and forms zinc silicate (2ZnO·SiO2) and zinc ferrite (ZnO·Fe2O3). ) into the slag. When refining miscellaneous copper materials with high zinc content (yellow copper, etc.), in order to accelerate the volatilization of zinc, the furnace temperature is increased during the melting period and the oxidation period (generally maintained at 1300 ~ 1350 ℃), and the surface of the melt is covered with a layer of charcoal or sulfur-free coke particles to reduce the zinc oxide to metallic zinc and volatilize, so as to avoid the formation of zinc oxide crust that hinders the zinc evaporation process. lead. Solid lead is insoluble in copper and rarely dissolves in the liquid state. However, during the oxidation period, when lead is oxidized into lead oxide, its density (9.2) is higher than that of copper (8.9), so it sinks to the bottom of the furnace. Therefore, if it is an acidic furnace bottom, PbO will interact with SiO2 in the furnace building material to generate lead silicate (XPbO·YSiO) with a low density. Thereby floating to the surface of the molten pool and being removed. If the furnace bottom is made of alkaline refractory material, it is very difficult to remove lead. At this time, quartz flux must be blown into the melt, the air volume must be increased, and the furnace temperature must be maintained at a high temperature (about 1250°C) to allow PbO and SiO2 to interact to produce lead silicate. The lead removal method using quartz slagging is time-consuming and the loss of copper entering the slag is large. In order to improve the lead removal effect and overcome the shortcomings of this method, phosphorus copper can be added to remove the lead in the form of phosphate. Boron oxide can also be used as a flux to remove lead in the form of lead borate. tin. When processing bronze materials, the material contains high tin content, and tin and copper dissolve in each other in liquid state. In the reverberatory furnace, tin is oxidized to generate stannous oxide (SnO) and tin dioxide (SnO2). SnO is weakly alkaline and can form slag with SiO2, and can also partially volatilize. SnO2 is weakly acidic and soluble in liquid copper. At this time, an alkaline solvent (soda or limestone) needs to be added to make it slagging to generate sodium stannate (Na2O·SnO2) or calcium stannate (CaO·SnO2) that is insoluble in liquid copper. Practice has proven that adding a mixed flux composed of 30% calcium oxide and 70% sodium carbonate can reduce the tin content in copper from 0.029% to 0.002%. Using a mixed flux of 50% Fe2O3 and 50% SiO2 can also quickly reduce the tin content to 0.005% and remove part of the lead. arsenic. It can be seen from the As ? Cu phase diagram that arsenic and copper are mutually soluble in the liquid state. During oxidation, arsenic can be oxidized into volatile As2O3, which is discharged with the furnace gas. However, a small amount of arsenic is also oxidized into As2O5 and generates copper arsenate (Cu2O · antimony. Antimony and copper are infinitely soluble in each other in the liquid state, and copper and antimony can also generate Cu3Sb and Cu3Sb2. Like arsenic, antimony also generates volatile Sb2O3 during oxidation, and can also generate Cu2O·Sb2O3 and Cu2O·Sb2O5 that are dissolved in copper liquid. Therefore, when dealing with miscellaneous copper containing high As and Sb, the oxidation and reduction process needs to be repeated several times to reduce the non-volatile As2O5 and Sb2O5 to the volatile As2O3 and Sb2O3. The non-volatile As and Sb must be treated with an alkaline flux. gold and silver. Gold and silver are completely enriched in the anode copper and enter the anode sludge during electrolytic refining. The anode sludge can be recycled through further processing. When all impurities are removed, the oxidation period ends and the process shifts to the reduction period. The first function of reduction is to reduce the peroxidized copper oxide to metallic copper, and the second is to remove the gas dissolved in the copper liquid. Because at the end of the oxidation, there is still about 8% Cu2O in the copper liquid. Too much oxygen in the copper will make the copper brittle and reduce its ductility and conductivity, so reduction must be carried out. During the reduction period, when heavy oil, wood cuttings, etc. are used for reduction, the main chemical reactions that occur are as follows:: 6Cu2O+2C2Hm=12Cu+2Co+mH2+2CO2 When reduced with NH3, the following reaction occurs: Cu2O+2NH3 6Cu+N2+3H2O If natural gas is used as the reducing agent, the natural gas must be so-called "reformed". Otherwise, methane CH4, a component of natural gas, decomposes at 1000°C to produce a large amount of H2. Although it can strengthen the reduction, it also increases the adsorption of hydrogen by copper.