CN-122012913-A - High-efficiency short-flow magnetizing roasting combined treatment method for iron ore

Abstract

The invention discloses a high-efficiency short-flow magnetizing roasting combined treatment method for iron ores, and belongs to the field of mineral processing engineering. The method comprises the steps of crushing and screening 0-300 mm iron ore, feeding the iron ore into a closed-circuit dry powder making system consisting of a high-pressure roller mill and a wind mill, obtaining qualified-grade ore powder, carrying out two-stage preheating on the ore powder, sequentially feeding the ore powder into a roasting furnace and a reduction furnace in a suspension state for magnetizing roasting, cooling high-temperature calcine by a waste heat boiler to recover heat, carrying out slurry making and pre-dressing tailing discarding on the cooled calcine, carrying out wet closed-circuit grinding by adopting a vertical stirring mill, and carrying out continuous magnetic separation and reverse flotation impurity removal to finally obtain high-quality iron concentrate. The invention combines the high-pressure roller mill dry milling and suspension roasting process, omits intermediate links such as filtration, drying and the like of the traditional wet milling, solves the problem of high energy consumption of wet ores in a furnace, and simultaneously adopts the high-pressure roller mill and the vertical stirring mill to realize the full-flow ball milling-free operation, thereby greatly improving the grinding efficiency and the energy efficiency level. Compared with the prior art, the method has the remarkable advantages of short flow, high efficiency, energy conservation, environmental protection and the like, and is particularly suitable for recycling low-grade refractory iron ores.

Inventors

• SUN HONGSHUO
• MENG TAO
• GAO ZEBIN
• CHEN YILIN
• QIN LINA
• GUO YI
• BIAN LIGUO
• CUI JIANHUI
• LI NING
• SU XIANTANG

Assignees

• 甘肃酒钢集团宏兴钢铁股份有限公司

Dates

Publication Date

20260512

Application Date

20260305

Claims (9)

1. 1. The combined treatment method for the high-efficiency short-flow magnetizing roasting of the iron ore is characterized by comprising the following steps of: Step 1, dry pulverizing S11, crushing and screening 0-300 mm iron ores in multiple sections to obtain 0-20 mm iron ores; S12, feeding the obtained 0-20 mm iron ore into a closed-circuit dry powder making system consisting of a high-pressure roller mill and a wind mill, sorting by the wind mill, and returning coarse fraction return ore to the high-pressure roller mill for regrinding, wherein qualified fraction mineral powder is used as suspension magnetization roasting ore feeding; step 2, suspension roasting S21, sequentially feeding qualified grain-grade mineral powder into a two-stage preheater for preheating; S22, sequentially feeding preheated mineral powder into a roasting furnace and a reduction furnace in a suspension state for magnetizing roasting, and carrying out gas-solid separation to obtain calcine; s23, cooling the high-temperature calcine to below 250 ℃ in a waste heat boiler under the protection of nitrogen, and recovering heat to generate steam; Step 3, grinding and magnetic separation S31, feeding the cooled calcine into a pulping tank to mix with water for pulping; s32, carrying out magnetic separation preselection tail discarding on pulp after pulp making; S33, carrying out wet closed circuit grinding on the pre-selected concentrate by adopting a vertical stirring mill, and then carrying out continuous magnetic separation to obtain magnetic concentrate; Step 4, reverse flotation S41, carrying out reverse flotation impurity removal on the magnetic concentrate, and carrying out rough concentration, concentration and scavenging to obtain the iron concentrate.
2. 2. The method according to claim 1, wherein the particle size distribution of the qualified size fraction ore powder in the step S12 is +0.5mm with a ratio of <2%, -74 μm with a ratio of 40% -55%, and-18 μm with a ratio of <30%.
3. 3. The method according to claim 1, wherein the suspension roasting furnace in step2 is a dry feeding furnace type, and the moisture content of the ore powder obtained in step S12 is less than 2.5%.
4. 4. The method according to claim 1, wherein when the water content of the iron ore fed by the high-pressure roller mill in the step S12 is more than or equal to 2.5%, the wind mill adopts hot air generated by an auxiliary heating system or hot flue gas of the suspension roasting furnace as a winnowing medium, so that the drying and the sorting are synchronously carried out.
5. 5. The method according to claim 1, wherein the inlet is sealed with a material blocking valve when the ore fines are fed to the preheating system in step S21.
6. 6. The method of claim 1, wherein the source of the drying medium of the two-stage preheater in step S21 is: The second-stage preheating uses 600-650 ℃ high-temperature flue gas discharged by a roasting furnace; the first stage preheating uses 300-380 ℃ medium-temperature flue gas separated after the second stage preheating.
7. 7. The method according to claim 1, wherein in step S22: the heat source of the roasting furnace is high-temperature flue gas generated by fully burning the gas Q, and the roasting temperature is 620-670 ℃; The reducing medium of the reducing furnace is gas Q, and the reducing temperature is 520-580 ℃.
8. 8. The method of claim 7, wherein the gas Q is one or more of metallurgical gas, water gas, natural gas, hydrogen.
9. 9. The method of claim 1, wherein the magnetic field strength of the magnetic separators used in steps S32 and S33 is 400-500 mt.

Description

High-efficiency short-flow magnetizing roasting combined treatment method for iron ore Technical Field The invention belongs to the technical field of mineral processing, and relates to a high-efficiency short-flow magnetizing roasting combined treatment method for iron ores. Background Iron ore is a basic raw material of the iron and steel industry, and stable supply thereof has important strategic significance for national economic construction. Along with the increasing exhaustion of the easy-to-select high-grade iron ore resources, the efficient development and utilization of lean, fine and miscellaneous refractory iron ores (such as fine-grain hematite, limonite, siderite and mixed iron ores containing iron carbonate) which account for the majority of the iron ore resource reserves in China are the core problems to be solved in the mineral separation field. Currently, magnetizing roasting-magnetic separation technology is recognized as one of the most effective treatment methods for refractory iron ores, especially weakly magnetic iron ores. The technology converts weak magnetic iron minerals (such as hematite and limonite) into strong magnetic magnetite, and then carries out high-efficiency recovery by magnetic separation. Around this technology, the existing technology mainly has the following technical routes: On one hand, the traditional magnetizing roasting process mostly adopts a shaft furnace or a rotary kiln, and has the problems of high energy consumption, small single machine processing capacity, high environmental protection pressure and the like. In order to improve the reaction efficiency, a suspension magnetization firing technique has been developed in recent years. For example, chinese patent application publication No. CN113042196a discloses a process for beneficiating hematite, which adopts a combined process of "stage grinding, coarse-fine classification, heavy-magnetic-floatation", and separates fine fraction from coarse-grained product by gravity separation to directly enter floatation, so as to avoid overgrinding. However, the process still has a longer flow, and the fine-fraction product still needs to undergo traditional wet ball milling and dehydration operation, so that the energy consumption and the water consumption are higher. On the other hand, in order to reduce the crushing and grinding energy consumption, high-pressure roller mills are introduced into the field of iron ore dressing as efficient and energy-saving crushing equipment. For example, chinese patent application publication No. CN112588430a discloses a short-flow high-efficiency separation process of carbonate-containing iron ore, which adopts two-stage continuous closed-circuit grinding, then carries out stirring grinding (ceramic ball medium) on mixed magnetic concentrate, and then carries out anion reverse flotation. Although the process shortens the flow and improves the grinding efficiency, the front-stage grinding still depends on the traditional ball mill, and is not systematically integrated with the magnetizing roasting process, and the energy consumption problem (such as wet ore feeding) of the roasting link is not effectively solved. In addition, for the treatment of mixed iron ore (symbiotic of magnetite and hematite), chinese patent publication No. CN113953080B proposes a beneficiation method, and magnetite in fine fraction products is preferentially separated by low-intensity magnetic separation so as to reduce the ore feeding amount and the medicament consumption of subsequent reverse flotation. Although the proposal is developed in the aspects of cost reduction and efficiency enhancement, the core ore grinding operation still adopts a closed-circuit system of a ball mill and a classifier, the energy utilization efficiency is relatively low, and the problem of high heat consumption of a suspension roasting system caused by feeding the moisture-bearing mineral aggregate into a furnace can not be fundamentally solved. In summary, although the prior art is optimized in local links such as crushing, grinding, sorting and the like, the following technical problems generally exist that 1) the process flow is long and generally comprises links such as multi-stage crushing, wet grinding, filtering, drying, scattering and the like, equipment investment and occupied area are large, 2) the crushing and grinding energy consumption is high, the traditional ball mill is still used as core grinding equipment, the energy utilization efficiency is still to be improved, 3) the energy efficiency of a roasting system is low, the water content of mineral powder after wet grinding is high, and the water evaporation absorbs a large amount of heat, so that the heat consumption of the system is increased. Therefore, the development of a novel process for efficiently treating the iron ore, which can organically integrate high-efficiency dry powder preparation, low-energy suspension roasting and fine grinding and selecting