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Three-stage suspension roasting-magnetic separation method for hematite-limonite mixed iron ores

A suspension roasting, iron ore technology, applied in chemical instruments and methods, magnetic separation, solid separation, etc., can solve the problems of poor sorting index, asynchronous reaction, inconsistent properties of iron ore, etc., to ensure the uniformity of reduction , Efficient recycling, the effect of improving the recovery rate

Inactive Publication Date: 2015-07-01
NORTHEASTERN UNIV
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AI Technical Summary

Problems solved by technology

[0004] Magnetization roasting-magnetic separation refers to heating materials or ores in the corresponding atmosphere to perform complex physical and chemical actions, so that weak magnetic iron minerals can be transformed into strong magnetic iron minerals (Fe 3 o 4 ), and then use the magnetic difference between minerals for magnetic separation; common magnetization roasting methods include shaft furnace roasting, rotary kiln roasting, fluidized roasting, etc.; Qiu Chongdong and others use flash magnetization roasting-weak magnetic separation process and chlorination roasting -Weak magnetic separation process to conduct a comparative test on Kunming Iron and Steel Baozipu red limonite; the test results show that the flash magnetization roasting-weak magnetic separation process can effectively improve the grade of iron concentrate, and the yield of iron concentrate is 55.27%, and the grade is 59.47% , a good index of recovery rate of 92.86%; the process of chlorination segregation-weak magnetic separation can obtain iron concentrate yield of 36.26%, iron grade of 77.24% (including P0.22%), and iron recovery rate of 80.20%. The recycling of chlorinating agents needs further research, and the process cost is relatively high, and many key engineering technologies need to be solved
[0005] When the above magnetization roasting technology is used to process hematite-limonite mixed ore, there are the following three problems: 1. Due to the inconsistency of the properties of iron minerals, the reactions of different minerals under the same reduction conditions are not synchronized, and the reduced materials cannot completely react to generate magnetic properties. Fe 3 o 4 , or there is over-reduction to generate non-magnetic FeO, which leads to poor sorting indicators; 2. The heating and reduction of materials are carried out simultaneously, and the reduction atmosphere is difficult to guarantee, and it is difficult to implement industrialization; 3. It cannot handle 0~25mm fine-grained materials

Method used

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  • Three-stage suspension roasting-magnetic separation method for hematite-limonite mixed iron ores
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  • Three-stage suspension roasting-magnetic separation method for hematite-limonite mixed iron ores

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Experimental program
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Effect test

Embodiment 1

[0045] The main components of the red-brown mixed iron ore (hematite-limonite mixed ore) are shown in Table 1 (unit wt%);

[0046] components TF FeO SiO 2 al 2 o 3 CaO content 35.25 1.03 49.41 0.15 0.39 components MgO P S K Na content 0.37 0.88 0.05 0.04 0.03

[0047] The chemical phase analysis results are shown in Table 2;

[0048] Table 2

[0049]

[0050] The method proceeds as follows:

[0051] 1. Pre-oxidation: Grind the red-brown mixed iron ore until the particle size is -0.074mm, accounting for 40% of the total weight, then put it into the suspension reaction furnace, and feed air into the suspension reaction furnace to make the material in a suspended state; The material in the suspension reaction furnace is heated to 800°C for pre-oxidation and roasting. At this time, the suspension reaction furnace is an oxidizing atmosphere, and the pre-oxidation time is 10s; the red-brown mixed iron ore is hematite-l...

Embodiment 2

[0058] Russet mixed iron ore grade 39% iron, containing 3% FeO, SiO by weight 2 15%;

[0059] Method is with embodiment 1, and difference is:

[0060] (1) Grind the ore until the particle size -0.074mm accounts for 50% of the total weight, heat to 700°C for pre-oxidation roasting, and the pre-oxidation time is 30s;

[0061] (2) The reduction time is 10 seconds; the volume flow ratio of CO and nitrogen is 1:5;

[0062] (3) When the temperature drops to 350°C, air is introduced into the suspension reaction furnace for reoxidation; the main component of the reoxidized material is magnetic iron γ-Fe 2 o 3 and Fe 3 o 4 ; where γ-Fe 2 o 3 The weight content is 80%, Fe 3 o 4 The weight content is 12%;

[0063] (4) When the part of the material after the second grinding to the particle size -0.044mm accounts for 50% of the total weight, the material after the second grinding is subjected to magnetic separation under the condition of a magnetic field strength of 70kA / m; the...

Embodiment 3

[0065] Russet mixed iron ore grade 33% iron, containing 4% FeO, SiO by weight percentage 2 20%;

[0066] Method is with embodiment 1, and difference is:

[0067] (1) Grind the ore until the particle size -0.074mm accounts for 60% of the total weight, heat to 600°C for pre-oxidation roasting, and the pre-oxidation time is 60s;

[0068] (2) The reduction time is 30 seconds; the volume flow ratio of CO and nitrogen is 1:3;

[0069] (3) When the temperature drops to 300°C, air is introduced into the suspension reaction furnace for reoxidation; the main component of the reoxidized material is magnetic iron γ-Fe 2 o 3 and Fe 3 o 4 ; where γ-Fe 2 o 3 The weight content is 60%, Fe 3 o 4 The weight content is 31%;

[0070] (4) When the part of the material after the secondary grinding to the particle size -0.044mm accounts for 60% of the total weight, the material after the secondary grinding is subjected to magnetic separation under the condition of a magnetic field streng...

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Abstract

The invention relates to a three-stage suspension roasting-magnetic separation method for hematite-limonite mixed iron ores and belongs to the technical field of mineral processing. The method comprises the following steps: (1) milling the hematite-limonite mixed iron ores, then, putting the milled material into a suspension reacting furnace, and enabling the material to be in a suspended state; heating to the temperature of 450-800 DEG C, so as to carry out preoxidation roasting; (2) stopping heating, and introducing nitrogen gas to displace air; introducing reductive gas, and enabling the material to be in a suspended loose state, so as to carry out reduction; (3) displacing unreacted residual reductive gas, introducing air to carry out reoxidation when the temperature is lowered to 250-400 DEG C, and then, taking out and carrying out secondary milling; (4) carrying out magnetic separation under the condition that the intensity of a magnetic field is 60-100kA / m. According to the method disclosed by the invention, the process is simple, the recovery ratio of highly-difficultly-separated ores is increased, the adaptability of the method is strong, the process is safe and reliable, and the product quality is uniform and stable; the method has the advantages of energy saving and consumption reducing.

Description

technical field [0001] The invention belongs to the technical field of mineral processing, in particular to a three-stage suspension roasting-magnetic separation method of reddish-brown mixed iron ore. Background technique [0002] With the rapid development of my country's iron and steel industry, the demand for iron ore has risen sharply; my country's iron ore has low grade, poor endowment, and high mining and dressing costs, resulting in domestic iron ore production far from meeting the needs of the development of the iron and steel industry; in 2014, my country imported There are 933 million tons of iron ore, and the dependence on foreign countries is as high as 78.5%. The high dependence of iron ore on foreign countries further reduces the international discourse power and safety of China Iron and Steel. In 2014, the price of imported iron ore has dropped from US$130 / t at the beginning of the year to below US$70 / t, and the price of domestic iron ore has also been reduced...

Claims

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Application Information

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IPC IPC(8): C22B1/02B03C1/00
Inventor 韩跃新李艳军高鹏
Owner NORTHEASTERN UNIV
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