Fabric Compensators And Oxygen Torch Melting

Oxygen-weighted or oxygen-torch melting (KVP or KFR) is a kind of autogenous method of suspended smelting of sulphide copper concentrates carried out in a suspended state. The main distinguishing features of this process are the use of technical oxygen as a blast and the burning of sulfides in a horizontal flare, as well as a tissue compensator.

The INCO process (VCT) originated primarily as a method for producing liquid sulfur dioxide of the day of the pulp and paper industry when processing sulphide copper concentrates. An autogenous smelting process using pure process oxygen (95% O2) as an oxidizer on an industrial scale has been carried out since 1953 at the Copper Cliff plant in Canada. A similar process was developed in the USSR and implemented at a copper plant in Almalyk (Uzbekistan). The main difference between CFP and PVP is that the crushed and deeply dried batch will be fed into the furnace through charge burners directed horizontally (there is no vertical melting shaft) and pure process oxygen is used as an oxidizing blast. The melting process is conducted with obtaining mattes of 45-55% (when getting a richer matte because of excess heat, the furnace overheats). The exhaust gases contain up to 80% SO2. Prospects for a broad industrial application of the INCO process is not.

The most important technological features of CFP are: the presence of a horizontal torch in the furnace increases the residence time of the particles in it, which theoretically should contribute to the intensification of the processes of oxidation of the particles of the processed batch, and also their heating and tissue compensators; Limited possibilities to regulate the degree of desulfurization towards its increase and impossibility of obtaining mattes with a copper content of more than 65-70% due to the allocation in this case of a large amount of excess heat and an increase in the temperature in the furnace to 1550-1600 ° C or more, which contributes to a sharp decrease Resistance to refractory masonry; Impossibility for the same reasons of a significant increase in the specific productivity of the smelting furnace; A small volume of rich sulfur dioxide produced during smelting, the theoretical content of SO2 can reach 90-95%. At KFP, the processed pulverized concentrate is introduced into the combustion space of the furnace by a stream of technical oxygen from Compens Elastik, which leads to the formation of a dust-gas flare in which materials are oxidized and melted. The process is completed by the formation in the bath of the furnace of a melt, which has been stratified into matte and slag. Finely dispersed dried concentrate in mixture with fluxes by a horizontal jet is blown by a special burner into the flame space of the furnace. The physico-chemical interactions between the charge components of the blast-furnace oxygen take place in the dust stream. Melt drops from the torch settle into the lower part of the furnace and form a liquid bath.

The following zones are installed in the KPF furnace:

- charge-oxygen torch, where oxidation of sulfides proceeds, in part the processes of shteyno-and slag formation (I);

- surface of the slag bath, where the flux is finally assimilated and the reaction of sulfides with oxides (II) proceeds;

- matte-slag bath, where the processes of matte and slag formation (II, III) are completed.

- fabric compensators

The charge of KPF furnaces consists of copper concentrate and quartz. The mixture is filtered and with a humidity of 12-16% dried in a drum to a residual concentration of 4-7%, while using expansion joints. The second stage of drying is carried out in vertical pipes by dryers, in the lower part of which hot gases are supplied, heated to 400-500 ° C at a speed of 12-14 m / s. The final humidity is 0.1-0.5%, the capacity of the dryers for the concentrate is 80-85 t / h, the moisture removes up to 4 t / h.

The high rate of oxidation processes, proportional to the phase contact surface, makes it difficult to adjust the matte composition and thermal melting conditions. Getting richer matte leads to the formation of excess heat and causes wear of the lining. For thermal control of the process, in this case it is necessary to reduce the productivity of the unit by concentrate. To increase the lining stability, the furnace coving and walls are coffered, the recycled materials (dust, converter slag) are processed, which allows to increase the copper content in matte without increasing the heat stress in the unit and fabric compensators.

Masonry furnace KPP is made of chromium-magnesite brick and compensators Compens-Elastic. Gas is removed from the furnace through a gas flue in the center of the combustion space of the unit. As a blast apply technological oxygen with a content of 95-98 vol. %. Stein, containing 40-50% copper, is discharged through the boreholes siphons into the buckets. The slag is poured through the tapholes into the slag trucks and sent to the dump. Oven gases and dust are sent through the connecting flue to the gas cooler. Dust is about 10% of the mass of the charge. The dust content of gases is 300-400 g / m³ at the inlet to the waste heat boiler and at the outlet from it - 200-250 g / m³.

CFP can also be successfully used for the processing of Cu-Zn-, Cu-Ni- and other sulphide concentrates.