A "magnetic-electric-flotation" integrated separation process for high-carbonate mixed iron ore

Abstract

The present invention relates to a "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore. The present invention combines the electric separation process with magnetic separation and flotation, and adds an electric separation process after the strong magnetic separation operation, so as to effectively remove ferrous carbonate in the mixed iron ore before the mixed iron ore enters the flotation process. Through the "magnetic - electric - flotation" combined separation process, the strongly magnetic magnetite in the mixed iron ore is separately selected by weak magnetic separation; at the same time, ferrous carbonate, which is easily slime - forming but has poor conductivity among the weakly magnetic minerals, is separated and removed by electric separation, reducing the content of ferrous carbonate in the iron ore entering the flotation process, improving the flotation operation index, and realizing the efficient development and utilization of high - carbonate mixed iron ore. Compared with the existing process, the method used in the present invention has a large variety of minerals in the ore to be treated, and can still effectively treat iron ore with a ferrous carbonate content greater than 10%.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral processing, and in particular to a "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore. Background Art

[0002] The average grade of iron ore resources in China is low, and most of them are complex and refractory iron ores with the characteristics of "poor, fine and miscellaneous". Among them, carbonate ores such as siderite (FeCO3) are often associated. Such ores have weak magnetism and are difficult to separate by strong magnetic separation operations. After entering the flotation process, a large amount of fine mud in the pulp will cover the surface of the minerals, resulting in a decrease in the selectivity of the reagents and a serious deterioration of the flotation index.

[0003] With the increase of the mining depth, the content of ferrous carbonate in the ores produced in the Anshan area of China is continuously increasing, and the content in some mining areas has reached more than 10%. At present, the combined process of "stage grinding, coarse - fine separation, gravity separation - magnetic separation - anionic reverse flotation" adopted by steel mill concentrators is difficult to separate such high - carbonate iron ores, and the flotation index drops seriously. There is even a phenomenon that the concentrate and tailings cannot be separated. The mining field has to mix the iron ores from different mining areas to reduce the content of iron carbonate in the feed materials (reduce it to less than 3%).

[0004] For example, the "ore dressing method for a high - carbonate mixed iron ore" disclosed in the patent document with the publication number CN106944248A grinds the raw ore and performs weak magnetic separation - strong magnetic separation to obtain weak magnetic separation iron concentrate and strong magnetic separation iron concentrate. The strong magnetic separation iron concentrate is screened by a fine screen to obtain qualified iron concentrate under the screen; the product on the screen is fed into a pre - classification - re - grinding - strong magnetic separation process to remove qualified tailings and obtain strong magnetic separation rough concentrate; the strong magnetic separation rough concentrate is fed into a positive flotation operation to obtain positive flotation iron concentrate and remove qualified tailings. The "ore separation method for an iron ore containing carbonate" disclosed in the patent with the publication number CN104014416B is carried out according to the following steps: 1) crushing the iron ore containing carbonate and performing primary ball milling and primary classification; 2) performing one - stage weak magnetic separation and one - stage strong magnetic separation on the overflow of the primary classification to obtain one - stage magnetic separation mixed rough concentrate, and discarding the tailings.

[0005] 3) Subject the magnetically separated mixed rough concentrate to secondary classification. After the sand from the secondary classification is fed into the second-stage ball mill, it is then mixed with the magnetically separated mixed rough concentrate from the first stage for classification; 4) Feed the overflow from the secondary classification into the second-stage weak magnetic separator and the second-stage strong magnetic separator for second-stage strong magnetic separation to obtain the second-stage magnetically separated mixed iron concentrate; 5) Subject the second-stage magnetically separated mixed iron concentrate to tertiary classification to obtain the coarse-grained mixed iron concentrate and the fine-grained mixed iron concentrate; 6) Then separately conduct reverse flotation on the coarse-grained mixed iron concentrate and the fine-grained mixed iron concentrate to obtain the coarse-grained concentrate and the fine-grained concentrate. The above two methods both use the combination of flotation method and magnetic separation method or gravity separation method to process the mixed iron ore. When the content of weakly magnetic minerals (ferrous carbonate) in the iron ore raw material is relatively high, the above methods cannot achieve good flotation indexes.

[0006] Therefore, it is urgent to invent an effective process to reduce the content of ferrous carbonate and improve the separation indexes of iron ore. Summary of the Invention

[0007] The object of the present invention is to provide a "magnetic-electric-flotation" combined separation process for high-carbonate mixed iron ore. Aiming at the current situation that the existing "magnetic separation-anionic reverse flotation" process flow is only limited to purifying iron ore with a ferric carbonate content of less than 3%, and it is difficult to process high-carbonate iron ore. The present invention combines the electroseparation process with magnetic separation and flotation, and adds an electroseparation process after the strong magnetic separation operation, so as to effectively remove ferrous carbonate in the mixed iron ore before the mixed iron ore enters the flotation process, reduce the influence on the flotation process, improve the separation indexes of iron ore, and realize the efficient development and utilization of high-carbonate mixed iron ore.

[0008] In order to achieve the above object, the present invention is realized by adopting the following technical solutions:

[0009] A "magnetic-electric-flotation" combined separation process for high-carbonate mixed iron ore, comprising the following steps:

[0010] 1) Use the particle product with a particle size of ≤3 mm after crushing and high-pressure roller grinding of the high-carbonate mixed iron ore as the raw ore and feed it into the grinding and screening operation to obtain a classified overflow product with a fineness of ≤0.075 mm accounting for 85% - 95%;

[0011] 2) Feed the overflow product into the weak magnetic pre-separation operation, the obtained concentrate enters the weak magnetic cleaning operation, and the tailings enter the strong magnetic separation operation;

[0012] 3) Feed the weak magnetic pre-separation concentrate into the multi-stage weak magnetic cleaning operation, and demagnetize between each stage of weak magnetic separation with a demagnetizer to obtain a high-grade magnetite concentrate. The tailings from the weak magnetic cleaning are merged and then fed into the reverse flotation operation;

[0013] 4) Feed the tailings from the weak magnetic pre-separation into the strong magnetic separation operation, the obtained strong magnetic separation concentrate is dried and then fed into the electroseparation operation, and the tailings are discarded;

[0014] 5) In the electrostatic separation operation, the obtained concentrate is fed into the reverse flotation operation, the tailings are discarded or subjected to magnetization roasting treatment, and the middlings are returned for re-selection;

[0015] 6) The weak magnetic separation tailings and the electrostatic separation concentrate are merged and then fed into the reverse flotation operation to obtain a high-grade magnetite-hematite mixed concentrate;

[0016] 7) The strong magnetic separation tailings, the electrostatic separation tailings, and the reverse flotation scavenging tailings are merged into comprehensive tailings.

[0017] The grinding methods in the grinding and screening operation include single grinding or a combination of multiple grinding methods such as high-pressure roller grinding, ball grinding, and agitation grinding.

[0018] In the above step 2), the weak magnetic pre-selection equipment selects a wet drum magnetic separator, and the magnetic field intensity should be determined according to the specific properties of the material and the requirements for the concentrate grade.

[0019] In the above step 3), the weak magnetic separation equipment selects one or a combination of a wet drum magnetic separator, a elutriator, and a magnetic vibrator. The magnetic field intensity during separation should be determined according to the specific properties of the material and the requirements for the concentrate grade; the number of stages in the weak magnetic separation operation can be determined according to the actual ore properties, generally set at 3 - 5 stages, and the obtained magnetite concentrate grade is not less than 66%.

[0020] In the above step 4), a high-gradient magnetic separator (such as the SLon series) is selected for the strong magnetic separation operation, and parameters such as the magnetic field intensity should be determined according to the specific properties of the material and the requirements for the concentrate grade; the number of stages in the strong magnetic separation operation can be determined according to the actual ore properties, generally set at 1 - 2 stages.

[0021] In the above step 5), a high-voltage drum electrostatic separator is selected for the electrostatic separation operation, and parameters such as the voltage (electric field) intensity should be determined according to the specific properties of the material and the requirements for the concentrate grade; the number of stages in the electrostatic separation operation can be determined according to the actual ore properties, generally set at 1 - 3 stages.

[0022] In the above step 6), the reverse flotation reagent system should be determined according to the specific properties of the material and the requirements for the concentrate grade; the number of stages in the reverse flotation operation can be determined according to the actual ore properties, generally one roughing, one cleaning, and three scavenging, the iron grade of the obtained magnetite-hematite mixed concentrate is not less than 67.5%, and the recovery rate of the flotation operation is not less than 80%.

[0023] In the above step 6), the weak magnetic separation tailings and the electrostatic separation concentrate are merged and mixed and then concentrated to control the feed concentration of the reverse flotation at 40% - 45%.

[0024] In the described high-carbonate mixed iron ore, the iron phase composition mainly contains hematite, magnetite, siderite (i.e., ferrous carbonate), etc., among which FeCO3 ≥ 3% by weight percentage.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] Through the "magnetic - electric - flotation" combined separation process, the strongly magnetic magnetite in the mixed iron ore is separately selected by weak magnetic separation; meanwhile, the ferrous carbonate, which is easily slime-forming but has poor conductivity among the weakly magnetic minerals, is separated and removed by electrostatic separation, reducing the content of ferrous carbonate in the iron ore fed to flotation, improving the flotation operation index, and realizing the efficient development and utilization of high - carbonate mixed iron ore. Compared with the existing processes, the method used in the present invention deals with ores containing a large variety of minerals, and can still effectively process iron ores with a ferrous carbonate content greater than 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the process flow diagram of the "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore of the present invention (Example 1). DETAILED DESCRIPTION OF THE INVENTION

[0028] The following further explains the specific implementation manners of the present invention with reference to the drawings:

[0029] Example 1:

[0030] As Figure 1 shown, the complex and refractory iron ore selected in this example is from Anshan area, Liaoning Province, with a total iron grade of 30.05%. Among them, calculated by mass percentage, magnetite contains 15.90%, hematite and limonite contain 16.87%, and siderite contains 13.95%. The separation is carried out using the process flow of the present invention.

[0031] 1) Feed the product of high - pressure roller grinding with a particle size of ≤3 mm into the ball mill, and form a closed - circuit grinding system with a hydrocyclone to obtain a product with an overflow particle size of 85% - 95% - 200 mesh.

[0032] 2) Feed the overflow product into the weak magnetic pre - separation operation. The obtained concentrate is subjected to three - stage weak magnetic cleaning operations, and is demagnetized by a demagnetizer between each weak magnetic separation stage to obtain a magnetite concentrate with a grade of 66.45%.

[0033] 3) Feed the tailings of weak magnetic pre - separation into a single - stage high - intensity magnetic separation operation, and discard the tailings.

[0034] 4) Feed the high - intensity magnetic separation concentrate into a single - stage electrostatic separation operation to obtain tailings mainly composed of FeCO3. The middlings are returned for re - separation in sequence, and the concentrate enters the reverse flotation operation.

[0035] 5) Combine the tailings of weak magnetic cleaning and the electrostatic separation concentrate and feed them into the reverse flotation operation (one roughing, one cleaning, and three scavenging operations) to obtain a magnetic - hematite mixed concentrate with an iron grade of 67.85% and a recovery rate of 82.55%.

[0036] 6) Combine the tailings of high - intensity magnetic separation, the tailings of electrostatic separation, and the tailings of reverse flotation scavenging as comprehensive tailings.

[0037] Example 2:

[0038] The complex refractory iron ore selected in this embodiment is taken from Anshan area, Liaoning Province, with a total iron grade of 25.69%. Among them, calculated by mass percentage, magnetite contains 21.55%, hematite and limonite contain 9.90%, siderite contains 6.55%, and gangue minerals are mainly quartz. The beneficiation is carried out using the technological process of the present invention.

[0039] 1) Feed the high-pressure roller mill product with a particle size of ≤3 mm into the ball mill, and form a closed-circuit grinding system with a hydrocyclone to obtain a product with an overflow particle size of 85% - 95% - 200 mesh.

[0040] 2) Feed the overflow product into the weak magnetic pre-separation operation. The obtained concentrate is subjected to four-stage weak magnetic concentration operation, and demagnetization is carried out by a demagnetizer between each stage of weak magnetic separation to obtain a magnetite concentrate with a grade of 66.8%.

[0041] 3) Feed the tailings of the weak magnetic pre-separation into a single-stage strong magnetic separation operation, and discard the tailings.

[0042] 4) Feed the concentrate of the strong magnetic separation into a two-stage electrostatic separation operation to obtain tailings with the main component of FeCO3. The middlings are returned for re-selection in sequence, and the concentrate enters the reverse flotation operation.

[0043] 5) Combine the tailings of the weak magnetic concentration and the concentrate of the electrostatic separation and feed them into the reverse flotation operation (one roughing, one cleaning, and three scavenging) to obtain a magnetic and hematite mixed concentrate with an iron grade of 67.66% and a recovery rate of 83.75%.

[0044] 6) Combine the tailings of the strong magnetic separation, the tailings of the electrostatic separation, and the tailings of the reverse flotation scavenging into comprehensive tailings.

[0045] Example 3:

[0046] The complex refractory iron ore selected in this embodiment is taken from Anshan area, Liaoning Province, with a total iron grade of 31.46%. Among them, calculated by mass percentage, magnetite contains 25.13%, hematite and limonite contain 15.75%, siderite contains 4.65%, and gangue minerals are mainly quartz. The beneficiation is carried out using the technological process of the present invention.

[0047] 1) Feed the high-pressure roller mill product with a particle size of ≤3 mm into the ball mill, and form a closed-circuit grinding system with a hydrocyclone to obtain a product with an overflow particle size of 85% - 95% - 200 mesh.

[0048] 2) Feed the overflow product into the weak magnetic pre-separation operation. The obtained concentrate is subjected to five-stage weak magnetic concentration operation, and demagnetization is carried out by a demagnetizer between each stage of weak magnetic separation to obtain a magnetite concentrate with a grade of 67.2%.

[0049] 3) Feed the tailings of the weak magnetic pre-separation into a two-stage strong magnetic separation operation, and discard the tailings.

[0050] 4) Feed the strong magnetic separation concentrate to a single-stage electrostatic separation operation to obtain tailings mainly composed of FeCO3. The middlings are sequentially returned for re-selection, and the concentrate enters the reverse flotation operation.

[0051] 5) Combine the weak magnetic separation tailings and the electrostatic separation concentrate and feed them into the reverse flotation operation (one roughing, one cleaning, and three scavenging operations) to obtain a magnetic and hematite mixed concentrate with an iron grade of 67.75% and a recovery rate of 81.26%.

[0052] 6) Combine the strong magnetic separation tailings, the electrostatic separation tailings, and the reverse flotation scavenging tailings into comprehensive tailings.

[0053] Example 4:

[0054] The complex refractory iron ore selected in this example is taken from the Yuanjiacun area in Shanxi. The total iron grade is 32.07%. Among them, calculated by mass percentage, magnetite contains 12.66%, hematite and limonite contain 26.83%, siderite contains 8.55%, and the gangue minerals are mainly quartz. The beneficiation is carried out using the process flow of the present invention.

[0055] 1) Feed the high-pressure roller mill product with a particle size of ≤3 mm into a ball mill and form a closed-circuit grinding system with a hydrocyclone to obtain a product with an overflow particle size of -200 mesh of 85% - 95%.

[0056] 2) Feed the overflow product into a weak magnetic pre-selection operation. The obtained concentrate is subjected to a three-stage weak magnetic separation operation, and demagnetization is carried out by a demagnetizer between each stage of weak magnetic separation to obtain a magnetite concentrate with a grade of 66.5%.

[0057] 3) Feed the weak magnetic pre-selection tailings into a two-stage strong magnetic separation operation, and discard the tailings.

[0058] 4) Feed the strong magnetic separation concentrate to a two-stage electrostatic separation operation to obtain tailings mainly composed of FeCO3. The middlings are sequentially returned for re-selection, and the concentrate enters the reverse flotation operation.

[0059] 5) Combine the weak magnetic separation tailings and the electrostatic separation concentrate and feed them into the reverse flotation operation (one roughing, one cleaning, and three scavenging operations) to obtain a magnetic and hematite mixed concentrate with an iron grade of 67.88% and a recovery rate of 82.65%.

[0060] 6) Combine the strong magnetic separation tailings, the electrostatic separation tailings, and the reverse flotation scavenging tailings into comprehensive tailings.

[0061] Example 5:

[0062] The ore sample selected in this example is obtained by mixing samples from multiple regions. After testing, the total iron grade is 37.63%. Among them, calculated by mass percentage, magnetite contains 20.74%, hematite and limonite contain 21.93%, siderite contains 15.05%, and the gangue minerals are mainly quartz. The beneficiation is carried out using the process flow of the present invention.

[0063] 1) Feed the product of high-pressure roller grinding with a particle size of ≤3 mm into a ball mill and form a closed-circuit grinding system with a hydrocyclone to obtain a product with an overflow particle size of 85% - 95% -200 mesh.

[0064] 2) Feed the overflow product into a low-intensity magnetic pre-separation operation. The obtained concentrate is subjected to a four-stage low-intensity magnetic cleaning operation, and demagnetization is carried out by a demagnetizer between each stage of low-intensity magnetic separation to obtain magnetite concentrate with a grade of 67.75%.

[0065] 3) Feed the tailings of low-intensity magnetic pre-separation into a two-stage high-intensity magnetic separation operation, and discard the tailings.

[0066] 4) Feed the concentrate of high-intensity magnetic separation into a three-stage electrostatic separation operation to obtain tailings with the main component of FeCO3. The middlings are returned for re-selection in sequence, and the concentrate enters the reverse flotation operation.

[0067] 5) Combine the tailings of low-intensity magnetic cleaning and the concentrate of electrostatic separation and feed them into the reverse flotation operation (one roughing, one cleaning, and three scavenging) to obtain magnetic and hematite mixed concentrate with an iron grade of 67.68% and a recovery rate of 82.75%.

[0068] 6) Combine the tailings of high-intensity magnetic separation, the tailings of electrostatic separation, and the tailings of reverse flotation scavenging into comprehensive tailings.

Claims

1. A "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore, characterized in that, It includes the following steps: 1) The granular product with a particle size of ≤3 mm after crushing and high-pressure roller grinding of high-carbonate mixed iron ore is fed into the grinding and screening operation as the raw ore to obtain a classified overflow product with a particle size of -200 mesh accounting for 85% to 95%; 2) The overflow product is fed into the weak magnetic pre-selection operation. The obtained concentrate enters the weak magnetic separation operation, and the tailings enter the high-intensity magnetic separation operation; 3) The weak magnetic pre-selection concentrate is fed into the multi-stage weak magnetic separation operation. Demagnetization is carried out by a demagnetizer between each stage of weak magnetic separation to obtain high-grade magnetite concentrate. The weak magnetic separation tailings are merged and fed into the reverse flotation operation; 4) The weak magnetic pre-selection tailings are fed into the high-intensity magnetic separation operation. The obtained high-intensity magnetic separation concentrate is dried and then fed into the electrostatic separation operation, and the tailings are discarded; 5) In the electrostatic separation operation, the obtained concentrate is fed into the reverse flotation operation, and the tailings are discarded or subjected to magnetization roasting treatment, and the middlings are returned for re-selection; 6) The weak magnetic separation tailings and the electrostatic separation concentrate are merged and fed into the reverse flotation operation to obtain high-grade magnetite-maghemite mixed concentrate; 7) The high-intensity magnetic separation tailings, the electrostatic separation tailings, and the reverse flotation scavenging tailings are merged into the comprehensive tailings.

2. The "magnetic - electric - flotation" combined separation process for a high - carbonate mixed iron ore according to claim 1, characterized in that, The grinding methods in the grinding and screening operation include single grinding or a combination of multiple grinding methods such as high-pressure roller grinding, ball grinding, and agitation grinding.

3. A "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore according to claim 1, characterized in that, In the above step 2), the weak magnetic pre-selection equipment selects a wet drum magnetic separator.

4. The "magnetic - electric - flotation" combined separation process for a high - carbonate mixed iron ore according to claim 1, characterized in that, In the above step 3), the weak magnetic separation equipment selects one or a combination of a wet drum magnetic separator, a washing machine, and a magnetic vibrating machine. The number of stages of the weak magnetic separation operation is set to 3 to 5 stages, and the grade of the obtained magnetite concentrate is not less than 66%.

5. A "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore according to claim 1, characterized in that, In the above step 4), the high-intensity magnetic separation operation selects a high-gradient magnetic separator.

6. The "magnetic - electric - flotation" combined separation process for a high - carbonate mixed iron ore according to claim 1, characterized in that, In the above step 5), the electrostatic separation operation selects a high-voltage drum electrostatic separator; the number of stages of the electrostatic separation operation is set to 1 to 3 stages.

7. A "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore according to claim 1, characterized in that, In the above step 6), the reverse flotation reagent system is one roughing, one cleaning, and three scavenging. The iron grade of the obtained magnetite-maghemite mixed concentrate is not less than 67.5%, and the recovery rate of the flotation operation is not less than 80%.

8. A "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore according to claim 1, characterized in that In the above step 6), the weak magnetic separation tailings and the electrostatic separation concentrate are merged and mixed and then concentrated to control the feed concentration of the reverse flotation at 40% to 45%.

9. A "magnetic - electric - flotation" combined separation process for high - carbonate mixed iron ore according to claim 1, characterized in that, In the described high-carbonate mixed iron ore, FeCO3 ≥ 3% by weight percentage.

Images