1. Neutral medium flotation without inhibitor. The process is mainly treated with the weak magnetic iron ore concentrate is magnetic, magnetic iron ore in order to reduce the content of 2 SiO. The addition of an amine-based cation collector , without the addition of an iron mineral inhibitor, is due to the poor floatability of magnetite in a neutral medium. Almost all of the foreign companies that implement magnetite anti-flotation and silicon reduction have adopted this process, such as the United States, Athens, Adams, Moose Mountain, and Griffith. and other processing plants. The characteristics of these flotation processes are: fine materials (-0.044 mm accounted for more than 90%), flotation and tailing, most of which have sweeping operations, and the iron grade of the floating materials is 63% to 66%. iron grade of 67% ~ 69% (SiO 2 content of 6% or less), the end of the floating iron grade from 23% to 35%, work-ferrous metals recovery of 93% to 96%. So far, China's selection of plants using this process is still relatively small. The anti-flotation workshop of Anshan Iron and Steel Co., Ltd., which was put into operation in the early 1980s, used a reverse flotation-foam magnetic separation tail-magnetic re-grinding process. The iron concentrate grade increased from 61.5% to 65.5%. Discontinued; in 2001, the second process of Angang Steel Changling Mining Company adopted the same process, the grade of iron concentrate increased from 65.5% to over 68.5%, and the SiO 2 content fell below 4%. The difference between the anti-flotation process of China's related plants and the foreign countries is that the reverse flotation does not end, but the magnetic separation is used. The sweeping operation is not set in the process. The granularity of the materials to be floated is coarse, and the mine needs to be reground. Re-election, the grinding amount is larger, the grinding efficiency is lower, and the operation yield is generally 96% to 98%. In addition, China has conducted research on the reverse flotation process of single oreamine collectors without inhibitors on raw ore or (weak, strong) magnetic separation concentrates of red iron ore, although small or semi-industrial tests have been successful. However, industrial trials failed to make breakthroughs due to the difficulty of handling flotation foam. Second, add inhibitor alkaline media flotation. The process is a relatively versatile process, especially suitable for the ore sorting of high-grade red iron or magnesia or red-red mixed ore, and also suitable for the sorting of coarse ore (magnetic fine or fine) of the above ore. Due to the flotation in an alkaline medium (pH 10 ~ 10.5), and the addition of iron mineral inhibitors, the mud resistance of the flotation is enhanced and the foam properties are greatly improved, so the flotation process can be set coarse, fine, sweeping The operation can guarantee the high-quality iron concentrate, and at the same time, it can be tailed in the sweeping operation, and the process operation is easy to control. Generally, the closed-loop process structure in which the medium-mineral concentrate returns or partially returns to the rough selection and re-selection is adopted. There are many red iron ore plants in the country. The typical concentrators include the Sept Iles plant in Canada and the Samarco plant in Brazil, both of which handle high grades. %-60%) of the original ore of red iron ore, the reverse flotation process is the same, the difference is that the former does not de-sludge directly for reverse flotation, while the latter is de-sludged by two-stage cyclone due to the large amount of primary slime. After the reverse flotation, the SiO 2 content of the iron concentrate was reduced to 5.5% and 2%, respectively, and the iron recovery rate was above 90%. In the last century, China's (weak, strong) magnetic separation concentrates such as Qi Dashan and other iron ore in Anshan Iron and Steel Co., Ltd. also carried out large-scale industrial experiments on similar processes. For ore mines with an iron grade of about 29%, iron grades of more than 65% can be obtained. The total recovery rate is more than 78% of the technical indicators, but due to the constraints of the current source of amine collectors and pollution of water quality, the process has not been industrially applied. With the development of technology, Xinyu Iron and Steel Company Tiekeng Iron Mine implemented a cationic collector floating silicon process for limonite strong magnetic concentrate in 2005. Design indicators: 37% of original ore grade, 54.5% of concentrate iron grade, comprehensive The recovery rate is 50%. It should be pointed out that the advantages of the cationic collector floating silicon process are: less variety of chemicals, lower cost, no need to carry out in high alkalinity medium, and little influence on filtration; disadvantages are: flotation foam is not easy to control It is sensitive to slime. The ammonia nitrogen in the amine collector is polluted by water quality, and the iron ore with more iron silicate mineral content is poorly sorted. Both domestic and foreign research and practice have proved that when iron-silicate silicate minerals (such as amphibole) are similar to the isoelectric point of useful iron minerals, when anionic collectors are used to float these iron silicate minerals, The result is a high foam grade and a large loss of useful iron minerals. This is a recognized technical problem in the industry at home and abroad, especially in recent years, how to solve this problem abroad has made a lot of research, and has made initial progress. Acid Violet dyes NINGBO YUNCAI CHEMICAL CO.,LIMITED , https://www.win-chemical.com