Copper matte is the product of copper smelting section, which is added to converting section as incoming material. If flash furnace or rotary flotation converting furnace is used in converting section, copper matte can only be put into furnace after granulation, grinding and drying. Guikuang Machinery, as the manufacturer of copper matte grinding mill, will introduce the application of copper matte vertical roller mill.
In the nonferrous metal pyrometallurgy industry, many processes will require materials to be injected into the smelting furnace by means of pneumatic conveying through nozzles. In order to ensure that materials pass through the nozzle quickly and coherently, raw materials need to be pretreated to make their particle size and water content meet the process requirements. In recent years, as an advanced and reliable grinding equipment, the vertical roller mill has been widely used in the raw material pretreatment in the field of non-ferrous smelting with its excellent grinding and drying performance. Because the nozzle of the furnace has high requirements on the particle size and moisture content of the materials to be fired, the particle size of the copper matte is required to be – 325 mesh, accounting for more than 80%, and the moisture content is less than 0.3%. Taking a copper smelting project using oxygen bottom blowing smelting rotary flotation converting process as an example, the project produces 250000 tons of cathode copper annually. The rotary flotation converting furnace receives copper matte to produce crude copper. The copper matte needs to be vertically ground into copper matte powder, and the design capacity is 80t/h. In this project, the technological process for preparation of copper matte powder is as follows: the granulated copper matte particles are measured by a quantitative feeder, and then sent to a rotary feeder for air locking before being sent to a vertical roller mill for powder preparation and drying. The powder is collected by a bag type dust collector, and then sent to the material bin on the top of the converting furnace by an embedded scraper conveyor. After the batching is measured, the copper matte particles are finally injected into the rotary flotation converting furnace for copper matte converting. The hot air in the grinding process is supplied by the hot air stove. The vertical roller mill is equipped with an automatic return system, and the return material generated by the abrasive is returned to the mill inlet by the bucket elevator. The whole system is controlled by micro negative pressure of induced draft fan.
Design key points of copper matte vertical roller mill: since the copper matte particles may be mixed with iron filings scattered during intermediate treatment such as grab bucket, the iron filings entering the vertical roller mill will affect the service life of the grinding roller, so two iron removal devices shall be added before feeding to prevent iron filings from entering the grinding mill. When drying the hot air furnace, a certain amount of cold air shall be added to the hot flue gas generated by the drying furnace to ensure that the temperature of hot air entering the bag filter is less than 150℃, so as to avoid burning through the bag. Generally, the particles of water quenched copper matte are uniform, but in production practice, the copper matte beard at the end of the chute will be mixed, and the volume is obviously larger than the copper matte particles after water quenching. These larger copper mattes will get stuck at the air lock feeder, which has a great impact on the continuity of the system. Therefore, it is necessary to detect and intercept large pieces of copper matte that do not meet the volume requirements to ensure continuous production.