Iron ore flotation process can be divided into alkaline medium flotation, flotation acid medium, alkaline - bis acidic flotation medium, the control dispersion - a base (acid) medium desliming flotation and selective flocculation - Acid In the process of medium flotation, since the floatability of minerals such as sulfur, phosphorus , fluorine and carbonate is similar to the floatability of iron minerals, iron ore containing such minerals is not suitable for the positive flotation process. Alkaline medium positive flotation process is the earliest research and industrial process. Generally, the pH of the slurry is adjusted to 9-10 with soda ash. The fatty acid is used as the collector . The typical application example is completed and put into operation in the 1950s. The Humbolt plant in the United States and the Donganshan plant in China. The outstanding feature of this process is that the process is simple and can be floated without mud removal. However, due to the small difference in floatability between iron minerals and gangue minerals in alkaline medium, it is difficult to obtain high quality iron concentrate. The process has undergone a lot of research and improvement work. For example, the Republic of the United States (Republic) plant uses thermal flotation process, the grade of iron concentrate can be increased from 61.5% to more than 66%; Michigan University of Technology uses composite modifier to control the dispersion of sludge-alkaline medium positive flotation process A semi-industrial test on the lean oxidized ore in the Lake Superior Lake region, the iron concentrate grade can be increased to more than 66%, and the SiO 2 content is reduced to about 4%; in order to eliminate Ca 2+ and Mg 2+ plasma in the floating slurry For the influence of selectivity, the Donganshan plant in China also carried out a softening water-flotation process test study. Due to the high production cost or unstable operation process of the above improved technology, it has not been widely applied in the industry. Since the 1960s, due to the large difference in the floatability of iron minerals and gangue minerals in weakly acidic media, foreign studies focusing on the positive flotation process of weakly acidic media have been successful, such as Groveland, USA. Germany (in Groveland) beneficiation plant with cyclones desliming - acid medium weak magnetic flotation tailings treatment process, the iron ore in the integrated SiO 2 content of 7.8% to 6.5%. In the 1970s, China began to study the positive flotation process of weakly acidic medium. In the early 1980s, it was put into production at the Qidashan Concentrator of Anshan Iron and Steel Co., Ltd. for the treatment of strong magnetic concentrate. The production practice proved that the change from alkaline to weakly acidic After flotation, the grade of integrated iron concentrate increased from 59% to over 63%. Due to the positive flotation process of weakly acidic medium, it is sensitive to slime, that is, the flotation material needs to be delimed, but the weak magnetic iron ore for fine particle inlay depends on strong magnetic separation, cyclone or natural desilting method. resulting in a large number of metal loss, and therefore our country since the 1980s carried out extensive research work in eliminating the influence of sludge. More representatively, the Maanshan Mine Research Institute has carried out selective flocculation and desalination-weak acid positive flotation process on the Donganshan lean red iron ore, controlled dispersion of slime-weak acid positive flotation process and alkaline-acidity. Research on double media positive flotation process. The results show that compared with the single weak alkaline positive flotation process, the iron concentrate grade can be increased by 2 to 4 percentage points under the premise that the iron recovery rate is basically unchanged. The above-mentioned improved process has not been widely applied in the industry on a large scale due to the lack of suitable selective flocculation equipment or complicated process control. Research and practice have proved that the positive flotation process of weakly acidic medium is obviously superior to the positive flotation process of alkaline medium in improving the quality of iron concentrate, and the concentrate is easy to be filtered. It should be said that this process is one of the major advances in flotation technology. However, the former process requires flotation desliming, and collector (petroleum sulfonate) consumption is large, resulting in higher costs dressing. Since the positive flotation process is relatively simple, it is possible to obtain a qualified iron concentrate under a relatively coarse grinding fineness, which is suitable for the selection of low-grade weak magnetic iron ore, so the process has been extended to this day. However, due to the positive flotation process, it is difficult to obtain the high-quality iron concentrate required by the modern steel industry, and the flotation requires high-concentration conditions to adjust the slurry, the cost of the flotation agent is high, and the green ball is thermally unstable during the process of the iron concentrate ball. Sex (ie heat sensitive), therefore, the further development of the process has been limited, for example, the relevant foreign selection plants have basically stopped production, and China's Donganshan plant has been transformed into re-election, strong magnetic separation, reverse flotation process.
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