Study On Selective Grinding Behavior Of Cassiterite Polymetallic Sulfide Ore

Selective grinding is referred to different grinding degrees of different minerals with unequal probability crushing characteristic in the grinding process of ore which is composed of various minerals. At the same time, most of the ore is composed of various minerals with different mechanical properties, so selective grinding is a common phenomenon in the grinding process and has important significance for improving the grinding efficiency and optimizing the size composition of grinding products.Cassiterite polymetallic sulfide ore is the main types of tin resources in China. It contains two types of valuable metal minerals which are cassiterite and sulphide ore. Because of their different mechanical properties and beneficiation methods, the over grinding of cassiterite and deficient grinding of sulfide minerals become the serious problems during the practical beneficiation process, which affects the recovery of cassiterite and decreases the concentrate grade of sulphide ore.In order to regulate and optimize the grinding technology in the beneficiation process of cassiterite of polymetallic sulfide ore, taking Dachang cassiterite polymetallic sulfide ore as the research object, the selective grinding behaviors of ball mill, rod mill and vibration mill under different grinding conditions were studied by means of batch grinding experiments in this paper. The results are as follows:(1)The selective grinding of a kind of mineral can be characterized by the change value of cumulative grade from grinding products with a certain size. When the change value is negative, it can be showed from the study that selective grinding happens in the grinding process of this mineral. On the contrary, if the change value is positive, this means that selective grinding does not happen. When the change value is zero, it can be inferred that this kind of mineral and the feeding are simultaneously ground. Similarly, the selective grinding of two kinds of minerals can be characterized by the change value of cumulative metal quantity of grinding products with a certain size. When the change value of a kind of mineral is negative and less than that of the other, it can be showed from the study that this mineral has stronger selective grinding. This characterization method only needs to calculate the yield of each size fraction and analyse the grade of valuable minerals in each size fraction, so this characterization method has many advantages such as simple calculation process, specific characterization meaning and intuitive characterization process.(2)Selective grinding behavior of polymetallic sulfide ore depends on not only the hardness of minerals, but also grinding time, grinding concentration, the type and rotation speed of mill.(3)Among the polymetallic sulfide ores used in the experiment, selective grinding is easier to take place in the Zn sulfide minerals, and the characteristic of selective grinding is more obvious than that of cassiterite.(4) When using ball mill for grinding, the selective grinding behaviors of Zn minerals and Sn minerals in the polymetallic sulfide ore are easier to take place in coarse fraction with the increase of grinding time. The differences of grinding between Zn minerals and Sn minerals decrease with the increase of grinding time, and increase with the increase of grinding concentration.(5) When using rod mill for grinding, the selective grinding behaviors of Zn minerals and Sn minerals in the polymetallic sulfide ore are easier to take place in coarse fraction with the increase of grinding time. The differences of grinding between Zn minerals and Sn minerals decrease with the increase of grinding time, and increase with the increase of grinding concentration.(6)When using vibration mill for grinding, the selective grinding behavior of Zn minerals in the polymetallic sulfide ore, are easier to take place in coarse fraction with the increase of grinding time, and the selective grinding rules of Sn minerals are just the reverse. The selective grinding behaviors of Zn and Sn minerals tend to be weaker at first and then stronger with the increase of grinding concentration. When grinding concentration is60%, selective grinding is the weakest. The grinding differences between Zn minerals and Sn minerals decrease with the increase of grinding time and concentration.(7)Among the three kinds of grinding machines used in the experiment, vibration mill has the most obvious selective grinding characteristic, followed by the ball mill, with the rod mill coming in the last. This is possibly related to not only the mechanical pressing way of the grinding machines and the motion state of materials in mills but also the specific energy on particles in grinding process.From what Ⅰ have mentioned above, we can come to a conclusion that the new characterization method is firstly used to quantitatively study the selective grinding behavior in China, and the systematic research on the selective grinding behavior of Zn sulphide ore and cassiterite in the polymetallic sulfide ore has certain innovation. These results have practical guiding significance in optimization of the grinding of polymetallic sulfide ore.