A new process technology for a limonite ore dressing

Kunming Bao Zipu steel iron ore 1,050,000 t / a beneficiation plant has been put into more than one year, the joint process of re-use magnetic iron production index of 29.15% fine mineral, grade _{TFe55.05%, PO.576%, SiO 2} 10.22% The theoretical recovery rate is only 50.87%, the concentrate grade and recovery rate are low, the phosphorus and silicon content are high, and the design index is quite different. The main reason is that the proportion of ore in the original design is 70% for hematite and 30% for limonite. In fact, the limonite of the Baozipu iron deposit covers the hematite and mines 12.24 million tons of hematite. It is necessary to produce 30 million tons of limonite. The production of hematite accounts for only 29%, and limonite accounts for 71%. In order to efficiently use the iron ore resources of Baozi, it is the key to study and develop the rational scheme of the brown iron ore in Baozi. This paper will do some exploration and thinking in the beneficiation experiment of the bunlite.

First, the nature of the ore

The iron minerals of the bunite iron ore are mainly limonite, and the inlaid grain size is generally between 0.005 and 0.2 mm, and the aggregate size of the limonite is not uniform, and the mosaic relationship with the gangue mineral is relatively close; gangue minerals are quartz, times as silk mica, feldspar and silicate minerals kaolinite, quartz grain size than the other coarse gangue minerals, multi between 0.02 ~ 0.4mm, sericite silicon The acid salt mineral has a fine particle size and is in the form of a fine scaly or granular aggregate, and the particle size is mostly between 0.01 and 0.1 mm. Phosphorus in the ore with independent phosphorus mineral-apatite is rare. Phosphorus is mainly distributed in the form of ion adsorption in limonite, accounting for 91.95% of the total amount of P. The characteristics will cause the use of mechanical beneficiation methods not only to reduce the phosphorus content of iron concentrate, but also with the tendency of the phosphorus content of iron minerals to increase slightly. The main mineral content in the ore is shown in Table 1. The chemical composition of the ore is shown in Table 2. The ore has a TFe/Fe0 ratio of 296.1 and a basicity of 0.01. The chemical phase analysis results of phosphorus are shown in Table 3.

Table 1 Content of main minerals in ore (mass fraction) /%

Table 2 Chemical composition of ore (mass fraction) /%

Table 3 Results of phosphorus phase analysis in ore

Second, Baozipu brown iron ore mechanical beneficiation test results

Over the years, many research institutes have carried out experimental research on the development and utilization of Baozipu iron ore. With the passage of time and the progress of mineral processing technology , the use of heavy, magnetic, floating and its combined processes and other mechanical beneficiation schemes The indicators of the mine have improved, but it is difficult to raise the quality of the iron concentrate of the limonite, mainly because the grade of the concentrate is low, and the content of phosphorus and silicon in the concentrate is high. Table 4 shows the results of the exploration experiment of the Baozipu beneficiation over the years. Tables 5 and 6 show the results of the ore dressing test indicators and the chemical composition analysis of the concentrates of the Kunming Institute of Metallurgy in 1980.

Table 4 Exploratory test results of Baozipu mineral processing over the years

Table 5 Beneficiation test indicators of red, brown and mixed ore in Kunming Institute of Metallurgy, 1980

Table 6 Multi-element analysis results (mass score)/% of the final product of limonite in Kunming Institute of Metallurgy, 1980

Experimental study on chemical beneficiation of brown iron ore in Baozipu

(1) Flash magnetization roasting-magnetic separation process

The flash magnetization roasting-magnetic separation process has solved the key technical problems of this process for the treatment of refractory composite iron oxide ore. In many complex iron oxide ore beneficiation mainly composed of limonite and siderite, good sorting technical indicators have been obtained.

The calcination test was carried out on a 500 kg/h flash magnetization roasting pilot plant. The temperature of the reactor was controlled at 850-900 °C, and the CO content of the reactor was controlled at 2% to 3%. After 1 h continuous test, every 15 min. The roasting ore is taken once, and the calcined ore is ground to -0.075mm to occupy 94.56% (-0.045mm fraction is 77.43%), the controlled magnetic field strength is 160 kA/m, and the roasting product inspection test is carried out in the magnetic separation tube. It is indicated that the browning iron ore after bake burning by flash magnetization can obtain better beneficiation index. The results of the flash magnetization roasting-magnetic separation process are shown in Figure 1.

Figure 1 Flash magnetization roasting - magnetic selection quality process

The flash magnetization roasting-magnetic separation process can obtain the index of 55.27% iron concentrate, 59.47% iron grade and 92.86% iron recovery.

(2) Chlorination Separation-Weak Magnetic Separation Process

According to the current research on the process of iron and phosphorus reduction in iron ore mines at home and abroad, the patent of chlorination segregation-weak magnetic separation process applied by Kunming Jingshi Mining and Metallurgy Co., Ltd. is especially effective for the beneficiation of high-phosphorus iron ore. A laboratory exploration experiment was carried out on the bunlite limestone mine by chlorination-separation-weak magnetic separation process. The test results are shown in Fig. 2. The chlorination segregation-weak magnetic separation process can obtain the index of 36.26% iron concentrate, 77.24% iron grade, 0.22% P, and 80.20% iron recovery. However, the recycling of chlorinating agents in this process is for further study. And the process cost is high, and it is necessary to study and solve many key technologies of engineering.

Figure 2 Chlorination Segregation-Weak Magnetic Separation Process Number Quality Process

Fourth, the conclusion

(1) Baozipu limonite belongs to iron ore with low iron, high phosphorus and high silicon acid oxidation. The phosphorus in the ore mainly occurs in the limonite in a relatively uniform state of ion adsorption. The general mechanical beneficiation method for the bunlite limestone mine is difficult to achieve products with an iron concentrate grade of 57% or more, phosphorus of less than 0.4%, and silicon of less than 5%.

(2) Magnetization roasting-magnetic separation is an ideal process for improving the grade of iron concentrate by buns laying limestone. Using this process, a good index of iron concentrate yield of 55.27%, iron grade of 59.47%, and iron recovery of 92.86% can be obtained.

(III) Exploration of chlorination segregation-weak magnetic separation process in the copper ore dressing of Baozipu. The laboratory test can obtain the iron concentrate yield of 36.26%, the iron grade of 77.24%, the P content of 0.22%, and the iron recovery rate of 80.20%. The indicator has a high grade of iron concentrate and a 60% reduction in phosphorus. However, the recycling of chlorinating agents needs further study, and the cost is high. It is necessary to study and solve many key technologies of engineering.

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