Most people are likely unfamiliar with mineral processing. The reason why I think so is that I have often encountered many people asking me some very basic questions about it. As I’m a worker in Yantai Xinhai Ming Machinery Co., Ltd, sometimes my friends and relatives around will habitually ask me some questions about mines and mineral processing which I think are very simple and basic questions. I have roughly sort out the questions at my leisure time and carefully chosen seven of them. I believe even people who never expose themselves to mineral processing industry can have a basic understanding through these seven questions.
Mineral processing is a process during which we make full use of the physical and chemical difference of minerals to separate the valuable minerals with gangue minerals and achieve the relative enrichment of valuable minerals by means of various beneficiation equipment. Three are several solutions of mineral process in Xinhai.
The ores mined from the underground are generally made up of valuable minerals and gangue minerals with a lower grade that cannot be directly smelt. Therefore, it is necessary to process them preliminarily by eliminating most gangues and harmful ingredients to enrich the minerals to concentrates for the sake of further utilization. That’s why mineral processing comes.
Minerals are native elements or natural compounds with fixed chemical constitution and physical and chemical properties that formed after the physical, chemical and biologic functions under natural environment factors in the crust. They are component part of rocks or ores.
Apart from few native elements like Au, Ag, Cu, S, C and so on, the vast majority of minerals are natural compounds, such as Fe3O4, SiO2, PbS, CuFeS2 and so on.
There are over 3500 types of the known minerals. However, under the existing technical conditions, only 200 of them can be used.
Only after the ores from quarries finishing the whole beneficiation process, can the final concentrate accord with the smelting requirements. The whole process is as shown in the figure below.
The beneficiation process mainly includes three steps, namely, preparation operation that consist of ores’ crushing-screening and grinding-classification, separating operation that consist of technologies like gravity separation, flotation and electrostatic separation, and dewatering operation that consist of concentration, filtration, drying, etc.
The grade of ores refers to the content of some metal or useful components the ores contain, usually described by percentage. There are three kind of ores grade: grade of raw ore, grade of concentrate and grade of tailings, which are respectively represented with α, β and θ. If there is something wrong with the mineral processing production, analyses will generally come first in these three kinds of grades.
The concentrates are the final products of concentration plants obtained after the ores’ separating operation by eliminating most gangues and impurities to fulfill the enrichment of the valuable minerals.
The tailings are the last products with few useful contents remained after all kinds of extractions and screening operations on the raw ores.
The middlings are the intermediate products obtained during the separating process. Their valuable contents are higher than those of concentrate but lower than tailings, so it’s necessary to return them for another separating operation or further deal with them separately so that they can be used efficiently.
The common mineral processing methods in beneficiation plants are gravity separation, flotation technology, magnetic separation and electrostatic separation.
The gravity separation is a separation method that is used in separating minerals according to their difference in relative density. The principle here is that the ore grains with different density will implement the separation under the appropriate loose layering and separating conditions caused by the effect that the fluid dynamics and various mechanical forces have on the ore grains in moving mediums like water, air and heavy fluid.
The flotation technology is a separation method which accomplishes the separation purpose by selectively absorbing the valuable minerals onto the foams with the help of flotation reagents in accordance with the difference in physical and chemical properties of the minerals surface. And flotation technology is usually adopted when processing the non-ferrous metals like copper, lead and zinc.
The magnetic separation achieves separation of minerals by making different minerals experience different forces in the magnetic field of magnetic separators on the basis of their different magnetism. This technology takes the lead in the separation of ferrous metal ores like iron, manganese, chrome, etc.
The electrostatic separation is conducted according to the various minerals conductivity. When minerals pass by the high-voltage electric field of the electrostatic separators, the minerals will separate because of the different electrostatic force arising from the diverse conductivity. Electrostatic separation method is mainly used for separation and concentration of mixed ores, including separation of wolframine and cassiterite and the concentration of zirconite.