2019-11-27(18:29:42)
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Copper minerals mainly include pyrite,chalcopyrite, tetrahedrite, chalcocite, azurite, malachite, etc. Among them, chalcopyriteis the main copper mining ore, followed by bornite and chalcocite. In this paper, we will introduce the common process and equipment used in the copper mining process.
At present, the copper mining process mainly includes following steps: firstly, crushing the raw ore to a certain size that the useful minerals realize full monomer dissociation by the crusher and grinding mill; Secondly, adopting the certain copper mining process and copper mining equipment to isolate the useful minerals according to ore properties. There are various kinds of copper ores with complex ore properties in the nature, and most copper minerals have good flotability, therefore froth flotation process is common copper mining process. Besides, wet-process copper extraction process is also an effective copper mining process.
Using the crusher to break the copper ore to a certain particle size, which meets the requirements of feeding size in grinding stage. The common crushing stage of copper mining process includes three stage crushing with single closed circuit stage, which is divided into coarse crushing, secondary crushing, fine crushing and screening. Screening stage can ensure the particle size of crushing products. Coarse crushing equipment usually includes gyratory crusher, jaw crusher; secondary crushing equipment usually has jaw crusher and cone crusher, and fine crushing equipment commonly uses cone crusher. Screening equipment often adopts circular vibrating screen or linear vibrating screen. Of course, there are some differences in the actual crushing process according to different ore properties.
Grinding is the further crushing process of the copper ore, which makes the useful minerals fully realize monomer separation and prepares for the subsequent separation. The main ore grinding process used in the copper mining process is two stage grinding process. a grinding stage often use grid type ball mill because of large processing capacity and coarser ore particle size, and second grinding has higher requirement for the particle size, so it is often processed in overflow type ball mill. In order to control the final grinding particle size, mill products are sent to spiral classifier or hydrocyclone for classifying, then fine products enter to the next operation, coarse products return to ball mill for regrinding. Sometimes, middling is required to further grinding in the separation process, which is usually carried on in small overflow ball mill.
The common copper mining processes are divided into froth flotation process and wet-process copper extraction process.
According to mineral separation sequence, froth flotation process can also be divided into differential flotation, bulk flotation, flotability ranking flotation, part-selective flotation, etc. According to flotation reagents, froth flotation process can be divided into direct flotation, sulfuration flotation.
Direct flotation process can be used for the separation and purification of copper sulphide ore and oxide copper ore,and sulfur atom in copper sulphide ore is the excellent solid-affinitive atomof xanthate collectors, which makes xanthate collectors can be absorbed on ore surface easily and increases its hydrophobicity, then float copper ore with flotation bubble. Direct flotation process is widely applied in the early copper ore flotation process, it is suitable for simple ore that is composed of gangues. It is featured with high recovery rate, poor selectivity, and is now gradually replaced by sulfide flotation process. The agents used in oxidized copper direct flotation have fatty acid, amine collector, chelating agent, thiol and other sulfur compounds. The flotation of oxide copper has higher requirements for gangue mineral types, which restricts the choice of collector.
Sulfide flotation process is suitable for the separation of copper oxide mining process. Copper oxide has poor flotability,which can be separated and purified by adding vulcanizing agent to make sulfurions adsorb on the ore surface, then using xanthate collectors to achieve separation. Sulfide flotation process can be divided into direct sulfide process and hydrothermal sulfide flotation process. Direct sulfide flotation process means to add sodium sulfide, sodium bisulfide, sulfuretted hydrogen, orcalcium sulfide to fine-grained copper ore, then use xanthate and aerofloat collector to recycle sulfur minerals. Hydrothermal sulfide flotation process means add sulphur to the pulp under the conditions of 180 ℃ and 0.6 ~ 1.0 Mpa,then oxide copper reacts with sulfur and generates sulfide scale for later collector adsorption. Sulfide flotation has advantages of not being restricted by gangue ore type, wide source of collector and low price.
Wet-process copper extraction process can be divided into acid leaching, amine leaching, microbiological leaching, etc.
According to the leaching way, they can be divided into underground leaching, heap leaching, and agitation leaching,biological leaching. According to the leaching reagents, they can be divided into acid leaching, amine leaching and microbiological leaching.
Acid leaching commonly uses dilute sulphuric acid as leaching agent, which can leach acid gangue-contained malachite, cuprite, tenorite, etc., this process is generally applied in low grade copper ore or copper mine tailings. Amine leaching is suitable for copper oxide ore with calcium-magnesium carbonate gangues, the leaching agents commonly use amine or amine salt, which is suitable for leaching raw ore,concentrate, middlings and tailings. The advantage of this process is leaching agent can be recycled. Microbiological leaching is a kind of sulphide copper leaching process. It mainly uses oxidative dissolution of some sulfur bacteriato sulfide, then recover copper element from leaching liquor.
The above is only brief introductions of copper mining processes and equipment. In practice, ore properties are very complex, and copper ore dressing processes are diverse. Froth flotation is generally conducted in all kinds of flotation cells and flotation columns,leaching process can be carried on in the leaching tank, or leaching liquid can be sprayed on copper ore directly, such as underground leaching, heap leaching,microbiological leaching.
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