An experimental method for efficient utilization of low-grade manganese iron ore

Abstract

The present invention discloses an experimental method for the efficient utilization of low-grade manganese iron ore. The method first performs a phase analysis on the low-grade manganese iron ore to identify the existing forms of manganese and iron therein; secondly, a differential thermal analyzer is used to detect the suitable decomposition temperature of the low-grade manganese iron ore; thirdly, the low-grade manganese iron ore is crushed and screened to separate lumps (>15 mm) and powders (<15 mm), which are then roasted separately at a roasting temperature corresponding to the decomposition temperature. The roasted lumps (>15 mm) are subjected to metallurgical property testing, the powders (<15 mm) are finely ground and magnetically separated, and the magnetically separated concentrate is used to produce acidic sintered ore using a sintering cup. The metallurgical properties of the acidic sintered ore and the roasted lumps (>15 mm) are tested, and an appropriate ratio of the roasted lumps (>15 mm) to the acidic sintered ore is selected based on the metallurgical performance indicators, thereby achieving the efficient utilization of the low-grade manganese iron ore.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical test research, and particularly relates to a test method for efficient utilization of low-grade manganese iron ore. Background Art

[0002] The original method for using low-grade manganese iron ore was to feed the lump ore directly into a small blast furnace, and the fine ore into a sintering machine to produce acidic sinter before feeding it into the blast furnace. This method resulted in an excessively high cracking rate of the raw ore after entering the furnace, resulting in large powders and poor charge permeability. Furthermore, the low grade of both the raw ore and the acidic sinter led to excessive slag volume, high fuel consumption, unstable blast furnace operation, and large production fluctuations. Therefore, it was necessary to improve the metallurgical properties of the raw ore and increase the grade of the sinter, thereby reducing slag volume and stabilizing blast furnace conditions. Summary of the Invention

[0003] The purpose of the present invention is to provide a test method for the efficient utilization of low-grade manganese iron ore to solve the problems existing in the above-mentioned background technology.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] An experimental method for efficient utilization of low-grade manganese iron ore comprises the following steps:

[0006] 1) Analyze the iron and manganese phases in low-grade ferromanganese ore using electron probe and mineral phase microscope to find out the existence forms of iron and manganese;

[0007] 2) Determine the decomposition temperature of low-grade manganese iron ore using a differential thermal analyzer and select the appropriate roasting temperature based on the decomposition temperature;

[0008] 3) First, crush the low-grade manganese iron ore to less than 60mm, use a 15mm sieve to screen the crushed manganese iron ore into >15mm lump ore and <15mm powder ore, and roast these two ores separately. Then use a 15mm sieve to screen the roasted >15mm lump ore, and combine the obtained <15mm powder ore with the separately roasted <15mm powder ore to finally obtain >15mm roasted lump ore and <15mm roasted powder ore;

[0009] 4) Take roasted ore blocks with a diameter of >15mm to conduct metallurgical property testing;

[0010] 5) Take roasted fine ore with a diameter of less than 15mm and perform fine grinding and magnetic separation to obtain magnetic concentrate. The magnetic concentrate is then used in a sintering cup to produce acidic sintered ore, and the metallurgical performance indicators of the acidic sintered ore are tested;

[0011] 6) Compare the metallurgical performance indicators of roasted lump ore >15mm and acidic sinter, and carry out metallurgical performance tests of different proportions of roasted lump ore and acidic sinter. Based on the test results, propose an appropriate combination of roasted lump ore and acidic sinter, so as to achieve efficient utilization of low-grade manganese iron ore.

[0012] Furthermore, the low-grade manganese iron ore has a total iron content of 30±1.5% and a manganese content of 12±1.5%. Both the iron and manganese contents are relatively low, so it is called low-grade manganese iron ore.

[0013] Furthermore, the analysis of the iron and manganese phases in low-grade ferromanganese ore using an electron probe and a mineralogy microscope was primarily aimed at identifying the forms of iron and manganese present. This analysis revealed that the iron and manganese were primarily present as iron carbonate and manganese carbonate, followed by magnetite and iron-manganese oxides. This suggests that the ferromanganese ore has poor magnetic properties, making it unsuitable for direct magnetic separation.

[0014] Furthermore, the differential thermal analysis (DTA) aims to determine the decomposition temperatures of iron carbonate and manganese carbonate in low-grade manganese iron ore. This is because iron carbonate decomposes into highly magnetic iron oxides at high temperatures, significantly improving magnetic separation efficiency. This facilitates magnetic separation and increases the iron and manganese grades. DTA analysis indicates that the decomposition temperature of low-grade manganese iron ore starts at 420°C and ends at 800°C, with an optimal roasting temperature of 650°C to 750°C.

[0015] Furthermore, the lump ore with a size of more than 15 mm and the powder ore with a size of less than 15 mm are roasted separately. The reason is that the air permeability of the material layer during the roasting process of the lump ore and the powder ore is different, and the roasting time required is different, so they need to be roasted separately.

[0016] Further, fine grinding and magnetic separation tests were conducted on roasted fine ore <15mm in diameter. The goal was to improve the iron and manganese grades of the magnetically separated concentrate, reduce the gangue content in the raw ore, and thus reduce the amount of slag during the smelting process. The magnetically separated concentrate obtained through fine grinding and magnetic separation had an iron recovery rate of 85%-89%, a manganese recovery rate of 75%-80%, and a yield of >75%.

[0017] Furthermore, the purpose of the metallurgical performance test is to detect and compare the metallurgical properties of roasted lump ore and acidic sintered ore in the blast furnace. Based on the metallurgical performance test results of the two, a matching scheme is proposed, and metallurgical performance testing is carried out on the matching materials. Through the test, it is concluded that the metallurgical performance indicators of roasted lump ore are better than those of acidic sintered ore. This is mainly manifested in that the melting start temperature of roasted lump ore is higher than that of acidic sintered ore, the melting range is narrower, the maximum pressure difference is smaller, and after the matching ratio of roasted lump ore and acidic sintered ore is increased to 35%, its metallurgical performance indicators are significantly improved compared with the use of acidic sintered ore alone. After it is increased to 60%, the improvement in the indicators is no longer significant. For this reason, it is proposed that the appropriate matching ratio of roasted lump ore is 35%~60%.

[0018] Metallurgical property testing is mainly for high temperature melting property testing. The principle is to place an iron ore sample of specified particle size and mass on a fixed bed, with coke of specified particle size and mass on top and bottom, add a load, and introduce a reducing gas composed of CO and N2, and heat it to 1600℃ according to a certain heating system. Record the softening start temperature (T 10 ), softening end temperature (T 40 ), melting start temperature (T s ), dripping temperature (T d )(no dripping temperature> 1580℃), maximum pressure difference ΔP, calculate the reflow interval ΔT1 (T 40 -T 10 ), calculate the melting range ΔT2 (T d -T s The test equipment used is an iron ore high temperature load reduction softening dripping measuring device.

[0019] The present invention has the following beneficial effects compared to the prior art:

[0020] This research method replaces raw lump ore with roasted lumps >15mm, reducing the decrepitation rate. The roasted ore also exhibits significantly better metallurgical properties than the raw ore, primarily due to a 15 percentage point increase in reducibility. Furthermore, the combined iron and manganese grades in the magnetic concentrate are approximately 10 percentage points higher than those in the raw fine ore. These factors contribute to reducing slag volume, improving the metallurgical performance of the charge, and ultimately lowering the blast furnace fuel ratio. DETAILED DESCRIPTION

[0021] The present invention is described in detail below through specific examples.

[0022] Example:

[0023] (1) Using electron probe and mineral microscope, it was found that the iron in low-grade manganese iron ore exists mainly in the form of iron carbonate, followed by magnetite, and a small amount exists in the form of iron silicate and iron sulfide. Manganese exists mainly in the form of manganese carbonate, followed by manganese iron oxide. The specific results are shown in Tables 1 and 2 below:

[0024] Table 1 Analysis results of iron phases in ore

[0025]

[0026] Table 2 Analysis results of manganese phase in ore

[0027]

[0028] (2) The decomposition temperature of low-grade manganese iron ore measured by differential thermal analyzer starts from 420℃ and ends at 800℃, among which the rapid decomposition temperature is concentrated in 550~700℃.

[0029] (3) Crushing low-grade manganese iron ore to less than 60 mm, using a 15 mm sieve to separate the crushed manganese iron ore into 15-60 mm lumps and <15 mm powder, and roasting these two types of ores separately. The roasting temperature is set at 700 ° C. Then, using a 15 mm pore size sieve to sieve the roasted lumps, ultimately obtaining roasted lumps >15 mm and roasted powder <15 mm.

[0030] (4) The roasted powder ore with a particle size of <15 mm was subjected to fine grinding and magnetic separation tests to obtain a magnetic concentrate with an iron recovery rate of 85-89%, a manganese recovery rate of 75-80%, and a yield of >75%.

[0031] (5) The magnetic concentrate is used in sintering cups to produce acidic sintered ore.

[0032] (6) The high-temperature load melting performance test was carried out on roasted ore with a diameter of >15 mm and acidic sintered ore. The results showed that the high-temperature load melting performance index of roasted ore was significantly better than that of acidic sintered ore. This was mainly manifested in that the melting start temperature of roasted ore was significantly increased from 1090℃ to 1250℃, the melting range was significantly reduced from 265℃ to 130℃, and the maximum pressure difference was significantly reduced from 9.5KPa to 1.6KPa. The results are shown in Table 3 below:

[0033] Table 3 Comparison of high temperature load remelting performance between roasted agglomerate and acidic sinter

[0034]

[0035] (8) Carry out metallurgical property tests of different proportions of roasted lump ore and acid sintered ore, as shown in Tables 4 and 5;

[0036] Table 4 Different ore ratios of roasted lump ore and acidic sintered ore

[0037]

[0038] Table 5 Droplet performance indicators of different ore ratios

[0039]

[0040] Tables 4 and 5 show that when the ratio of roasted lump ore increases to 35%, metallurgical performance indicators improve significantly, as evidenced by a significant increase in melting onset temperature, a significant decrease in melting range, and a significant decrease in maximum pressure difference. This improvement becomes less pronounced after the ratio of roasted lump ore increases to 60%. Therefore, the optimal ratio of roasted ore is 35%-60%. This effectively utilizes low-grade ferromanganese ore.

Claims

1. A test method for efficient utilization of low-grade manganese iron ore, characterized in that: The following steps are involved: 1) Analyze the iron and manganese phases in low-grade ferromanganese ore using electron probe and mineral phase microscope to find out the existence forms of iron and manganese; 2) Determine the decomposition temperature of low-grade manganese iron ore using a differential thermal analyzer and select the appropriate roasting temperature based on the decomposition temperature; 3) First, crush the low-grade manganese iron ore to less than 60mm, use a 15mm sieve to screen the crushed manganese iron ore into >15mm lump ore and <15mm powder ore, and roast these two ores separately. Then use a 15mm sieve to screen the roasted >15mm lump ore, and combine the obtained <15mm powder ore with the separately roasted <15mm powder ore to finally obtain >15mm roasted lump ore and <15mm roasted powder ore; 4) Take roasted ore blocks with a diameter of >15mm to conduct metallurgical property testing; 5) Take roasted fine ore with a diameter of less than 15mm and perform fine grinding and magnetic separation to obtain magnetic concentrate. The magnetic concentrate is then used in a sintering cup to produce acidic sintered ore, and the metallurgical performance indicators of the acidic sintered ore are tested; 6) Compare the metallurgical performance indicators of roasted lump ore >15mm and acidic sinter, and carry out metallurgical performance tests of different proportions of roasted lump ore and acidic sinter. Based on the test results, propose an appropriate combination of roasted lump ore and acidic sinter, so as to achieve efficient utilization of low-grade manganese iron ore.

2. The method for efficiently utilizing low-grade manganese iron ore according to claim 1, wherein: In step 1), the low-grade manganese iron ore has a total iron content of 30±1.5% and a manganese content of 12±1.5%; the iron and manganese exist mainly in the form of iron carbonate and manganese carbonate, and secondly in the form of magnetite and iron-manganese oxide.

3. The test method for efficient utilization of low-grade ferromanganese ore according to claim 1, characterized in that: In step 2), differential thermal analysis shows that the decomposition temperature of low-grade manganese iron ore starts from 420°C and ends at 800°C, and the suitable roasting temperature is 650°C~750°C.

4. The test method for efficient utilization of low-grade ferromanganese ore according to claim 1, characterized in that: In step 5), the iron recovery rate of the magnetic separation concentrate is 85% to 89%, the manganese recovery rate is 75% to 80%, and the yield is >75%.

5. The test method for efficient utilization of low-grade ferromanganese ore according to claim 1, characterized in that: In step 6), the appropriate proportion of roasted lump ore is 35% to 60%.

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