A low-sulfur lean magnetite desulfurization production process method

Abstract

The present application belongs to the technical field of metallurgical mine beneficiation, and is a low-sulfur lean magnetite desulfurization production process method. When mining and ore matching, 1) the assay of raw ore sulfur and concentrate sulfur needs to be increased in the ore sample of the mining site; 2) the upper limit of the sulfur content of the raw ore in mining and ore matching should not be higher than 0.12%; 3) the mining and ore matching indexes and their order are sulfur > selectability > grindability > MFe grade > dry separation tailing rejection rate; 4) the ore matching principle is: taking the grade as the core to match other indexes, and when the grade is qualified, the other indexes are calculated inversely, sampling points are added at the one-stage grinding classification and the final output concentrate in the stage grinding and stage separation process to master the sulfur index, if there is a phased anomaly, the mining adjustment and ore matching organization scheme or the emergency scheme is notified in time, and under the premise of ensuring the mining recovery rate, the product quality is qualified and the grinding efficiency is maximized, the final output sulfur content is realized below 0.05%, and the pollution of the sulfur content and the increase of the flotation desulfurization process to the environment is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgical mining and ore dressing, and particularly relates to a desulfurization production process method for low-sulfur lean magnetite. BACKGROUND

[0002] In the black metallurgical mining industry, iron ore with sulfur content less than 1% is low-sulfur ore, and the sulfur content of the iron concentrate is generally required to be less than 0.06% for the first-grade ore. However, in recent years, with the further strengthening and improvement of the national environmental protection, the discharge of toxic and harmful pollutants in industrial production is increasingly strict in the post-process iron-making plant, and it is required to control the sulfur content of the iron concentrate to be below 0.05%.

[0003] At present, there are the following methods for the desulfurization and iron separation process of iron ore:

[0004] 1. For the iron ore with fine grinding particle size and single pyrite and pyrrhotite associated with sulfur, a stage grinding-stage separation desulfurization process is adopted;

[0005] 2. For the strong magnetic iron ore with various types of sulfur, a magnetic separation-floatation combined desulfurization process is suitable;

[0006] 3. For the weak magnetic iron ore with low MFe grade and various types of sulfur, or limonite and rhombohedral ore, a roasting-magnetic separation-floatation combined desulfurization process can be adopted.

[0007] For the low-sulfur lean magnetite with pyrite as the main sulfur occurrence and pyrrhotite as the auxiliary sulfur occurrence, through sample screening analysis, it is found that the sulfur mainly exists in the particle size of-0.03 mm, and the content is 0.18%, and the distribution rate is as high as 48% or more. And with the decrease of the particle size, the sulfur content slightly increases, so it is difficult to adopt the fine grinding-magnetic separation separation desulfurization method, and the current realization of the sulfur content less than 0.05% can only adopt the magnetic separation-floatation combined desulfurization process, which inevitably increases the floatation process and the floatation reagent cost of at least 10 yuan / t, and the floatation reagent also has different degrees of influence on the concentrate filtrate water quality.

[0008] Therefore, it is necessary to develop a new production process method for the desulfurization of low-sulfur lean magnetite, which has practical significance for reducing the sulfur content, reducing the production cost and reducing the environmental pollution.

[0009] The purpose of the application is to overcome the shortcomings of the above production process technology, and provide a production process method for realizing the sulfur content less than 0.05% without increasing the cost by using the production process of "mining and ore matching" + "stage grinding-stage separation". SUMMARY

[0010] The purpose of the application is to overcome the shortcomings of the above production process technology, and provide a production process method for realizing the sulfur content less than 0.05% without increasing the cost by using the production process of "mining and ore matching" + "stage grinding-stage separation".

[0011] The purpose of the present application is achieved in that: 1. A low-sulfur lean magnetite desulfurization production process method, comprising the following steps: step one: sampling the ore in the stope, testing the sulfur index of the raw ore, and at the same time, carrying out stage grinding-stage separation desulfurization test on the raw ore, and testing the sulfur index of the concentrate, if the test result is that the sulfur of the concentrate is lower than that of the raw ore, then the normal grinding and separation process is carried out; if the sulfur of the concentrate is higher than that of the raw ore, then the following step is carried out; step two: organizing stage grinding-stage separation desulfurization test, determining that the upper limit of the sulfur content of the raw ore in the stope is 0.12% or less; step three: determining the organization rules, process correction and monitoring rules, and abnormal early warning mechanism of the stope sulfur allocation; step four: determining the stope ore allocation index and its order according to the primary and secondary factors affecting the index, which are in turn: sulfur > selectability > grindability > MFe grade > dry separation tailing rate; step five: determining the target of the stope ore allocation index and its ore allocation method, which are as follows:

[0012] 1) Monthly ore loss rate ≤ 5%,

[0013] 2) MFe grade of the raw ore entering the mill is within the daily qualified interval of the monthly plan grade ± 1%,

[0014] 3) MFe grade of the raw ore entering the mill is within the monthly qualified interval of the monthly plan grade ± 0.25%,

[0015] 4) Daily ore allocation index: 1.1 ≥ KM ≥ 0.87, 1.2 ≥ KX ≥ 0.9, S ≤ 0.08%,

[0016] 5) Monthly dry separation tailing rate ≤ 14%, and single-day dry separation tailing rate ≤ 18%,

[0017] 6) Powder ore should not be concentrated into the shaft to ensure the safe operation of the chute; step six: the ore allocation principle is: first allocate MFe grade, then calculate other indexes when MFe grade is qualified, adjust the ore quantity when a certain index is unqualified to ensure that all indexes are qualified, and allocate ore according to this scheme when all indexes are qualified, and when there is a conflict between indexes, ensure that the sulfur content is qualified first, and when other indexes are unqualified, warn the mineral processing process, and the calculation method is:

[0018] P = (P1*K1+P2*K2+P3*K3+P4*K4) / (K1+K2+K3+K4)

[0019] KM = (KM1*K1+KM2*K2+KM3*K3+KM4*K4) / (K1+K2+K3+K4)

[0020] KX = (KX1*K1+KX2*K2+KX3*K3+KX4*K4) / (K1+K2+K3+K4)

[0021] S = (S1*K1+S2*K2+S3*K3+S4*K4) / (K1+K2+K3+K4)

[0022] G = (G1*K1 + G2*K2 + G3*K3 + G4*K4) / (K1 + K2 + K3 + K4)

[0023] Wherein: P: MFe grade, KM: comprehensive grindability index

[0024] KX: comprehensive washability index, S: comprehensive sulfur index, G: dry separation tailing rate, P1: MFe grade of ore block 1, KM1: grindability index of ore block 1, KX1: washability index of ore block 1, S1: sulfur index of ore block 1, G1: dilution, i.e. dry separation tailing rate of ore block 1, K1: ore quantity of ore block 1;

[0025] P2: MFe grade of ore block 2, KM2: grindability index of ore block 2, KX2: washability index of ore block 2, S2: sulfur index of ore block 2, G2: dilution, i.e. dry separation tailing rate of ore block 2, K2: ore quantity of ore block 2;

[0026] P3: MFe grade of ore block 3, KM3: grindability index of ore block 3, KX3: washability index of ore block 3, S3: sulfur index of ore block 3, G3: dilution, i.e. dry separation tailing rate of ore block 3, K3: ore quantity of ore block 3;

[0027] P4: MFe grade of ore block 4, KM4: grindability index of ore block 4, KX4: washability index of ore block 4, S4: sulfur index of ore block 4, G4: dilution, i.e. dry separation tailing rate of ore block 4, K4: ore quantity of ore block 4; Step seven: sulfur organization ore blending principle: first calculate each index according to the ore blending principle, and then organize the ore after all the indexes are qualified, and ensure the sulfur content and MFe grade are qualified for special unqualified, ensure the ore quantity, and develop special control measures for the sulfur index.

[0028] The special control measures for the sulfur index in step seven are as follows:

[0029] 1) Strictly according to the ore blending principle of "sulfur > washability > grindability > MFe grade > dry separation tailing rate", the dispatching department cannot adjust the shovel position to organize ore blending;

[0030] 2) When organizing the ore, the sulfur content on the medium hole diagram must be followed, and the ore blast pile that has just been blasted but not yet mapped cannot be privately organized, and the ore can only be blended after the sulfur content index is obtained;

[0031] 3) The medium hole diagram is issued within one day after the test results are obtained to ensure the accuracy of ore blending;

[0032] 4) The medium hole diagram is refined and sent to the dispatching room within one day after being issued, and the dispatcher is required to be familiar with the medium hole diagram for ore blending and correspond to the site to ensure the accuracy of ore blending;

[0033] 5) Strictly control high-sulfur heap, organize ore drawing with ore matching truck, and according to the dressing test result, if the result is in the controllable range, that is, S content is less than or equal to 0.05%, the ore drawing can continue to be organized; if the test result is high, that is, S is greater than 0.05%, the ore drawing of the high-sulfur heap is immediately stopped, and in the next production organization, on the one hand, the sampling and testing scheme of the high-sulfur area is refined, and on the other hand, the emergency scheme is adjusted and started:

[0034] ① High-sulfur ore matching operation is organized with one truck per hour, that is, 115-135 tons, and the operation is suspended after one day of ore drawing, and the final output concentrate sulfur result is waited,

[0035] ② During the period of high-sulfur ore into the well, the ore dressing process does not switch the silo,

[0036] ③ During the period of high-sulfur ore into the well, the final output concentrate sulfur test frequency is adjusted from 1 time / 6h to 1 time / 2h;

[0037] 6) When the sulfur content appears an abnormal situation, that is, S is greater than 0.05%, the ore drawing shovel position must be immediately adjusted to change the original ore matching scheme, that is, the ore drawing strip is changed, the reason is found on site and analyzed, and the shovel position causing the abnormal S content is shifted or the digging direction is changed;

[0038] 7) After the low-sulfur lean magnetite adopts the desulfurization production process method of “mining and ore matching”+“stage grinding and stage separation”, the sulfur content of the overflow product of the first stage grinding and classification is between 0.1% and 0.3%, after the second stage grinding and the third stage grinding and four times of magnetic separation, the throw-off rate of the raw ore sulfur is 65-80%, and the final concentrate sulfur content is less than 0.05% per 6 hours.

[0039] The beneficial effects of the present application are: for the low-sulfur lean magnetite with less than 1% of sulfur content mainly in the form of pyrite and auxiliary in the form of pyrrhotite, the production process method of “mining and ore matching”+“stage grinding and stage separation” is adopted to control the concentrate sulfur content below 0.05%, the ore recovery rate is increased from 96% to 96.5%, the utilization coefficient of the ore dressing ball mill reaches 4.25t / tim 3 , the MFe metal recovery rate is 95.6%, and the output concentrate quality indexes TFe grade is 67% and SiO2 is 6%. Under the premise of not affecting the grinding efficiency and grade, the flotation desulfurization process transformation and flotation reagent cost are reduced, the environmental pollution caused by the flotation reagent is avoided, and the strict requirements of the ironmaking process on the sulfur content index are met. BRIEF DESCRIPTION OF DRAWINGS

[0040] The present application will be further described below in combination with the drawings.

[0041] Figure 1 is the hole chart in the mining and ore matching of the present application.

[0042] Figure 2is a low-sulfur lean magnetite "mining matching" + "stage grinding-stage separation" desulfurization production process flow chart. DETAILED DESCRIPTION

[0043] The application discloses a low-cost desulfurization production method for low-sulfur lean magnetite through stage grinding-stage separation after mining matching. The low-sulfur lean magnetite referred to in the application is a relatively single low-sulfur lean magnetite with a sulfur content less than 1%, mainly in the form of pyrite and secondarily in the form of pyrrhotite, and the desulfurization production process method comprises the following steps: 1) when mining matching, increasing the assay of the sulfur content of the ore in the stope and the sulfur content of the concentrate; 2) the upper limit of the sulfur content of the ore in the stope during the mining matching should not be higher than 0.12%; 3) the mining matching indexes and their sequence are sulfur > selectability > grindability > MFe grade > tailing rate of dry separation; 4) the matching principle is to match other indexes with the MFe grade as the core, to recalculate other indexes when the grade is qualified, to adjust the ore quantity when a certain index is unqualified to ensure that all indexes are qualified, and to match the ore according to the scheme when all indexes are qualified. When there is a conflict, the sulfur content index is given priority to be qualified. In the stage grinding-stage separation process, sampling points are added at the first-stage grinding classification and the final output concentrate to master the sulfur index, and if there is a phased anomaly, the mining adjustment matching organization scheme or the emergency scheme is notified in time to ensure that the sulfur of each batch is qualified.

[0044] 1. A technician samples the ore in the stope, assays the ore sulfur index, and simultaneously carries out stage grinding-stage separation desulfurization test on the ore, and obtains the concentrate S index. If the test result shows that the concentrate sulfur is lower than the ore sulfur, it indicates that the sulfur minerals can be removed through the normal grinding and separation process, and the ore in the stope can be normally matched for mining; if the test result shows that the concentrate sulfur is higher than the ore sulfur, it indicates that the sulfur in the ore is mainly in the form of pyrrhotite, and the stage grinding-stage magnetic separation process will cause the enrichment of sulfur, and the ore in the stope should be mainly matched for mining in a small amount. Through the assay of the ore sulfur and the concentrate sulfur, the distribution of the sulfur in the ore in the stope can be mastered, thereby providing a basis for the mining matching of the sulfur.

[0045] 2. The stage grinding-stage separation desulfurization test is organized to determine that the upper limit of the ore sulfur matching in the stope is below 0.12%.

[0046] 3. The organization rules, process correction and monitoring rules and abnormal early warning mechanism of the ore sulfur matching in the stope are determined.

[0047] 4. According to the primary and secondary factors of the indexes, the mining matching indexes and their sequence are determined as follows: sulfur > selectability > grindability > MFe grade > tailing rate of dry separation.

[0048] 5, The target of the mining and ore blending index and its ore blending method are determined as follows: 1) the monthly ore loss rate is less than or equal to 5%; 2) the MFe grade of the raw ore entering the mill is within the daily qualified range of the monthly plan grade ± 1%; 3) the MFe grade of the raw ore entering the mill is within the monthly qualified range of the monthly plan grade ± 0.25%; 4) the daily ore blending index: KM≥0.87, KX≥0.9, S≤0.08%; 5) the monthly dry separation tailing rate is less than or equal to 14%, and the single-day dry separation tailing rate is less than or equal to 18%; 6) the powder ore should not be concentrated into the shaft to ensure the safe operation of the shaft.

[0049] 6, The ore blending principle is: first blend MFe grade, take MFe grade as the main index, and then calculate other indexes. When a certain index is unqualified, adjust the ore quantity to ensure that all indexes are qualified. When all indexes are qualified, blend the ore according to this scheme. When there is a conflict between indexes, give priority to ensuring the sulfur content, and give a warning to the beneficiation process when other indexes are unqualified. The calculation method is: P=(P1*K1+P2*K2+P3*K3+P4*K4) / (K1+K2+K3+K4)

[0050] KM=(KM1*K1+KM2*K2+KM3*K3+KM4*K4) / (K1+K2+K3+K4)

[0051] KX=(KX1*K1+KX2*K2+KX3*K3+KX4*K4) / (K1+K2+K3+K4)

[0052] S=(S1*K1+S2*K2+S3*K3+S4*K4) / (K1+K2+K3+K4)

[0053] G=(G1*K1+G2*K2+G3*K3+G4*K4) / (K1+K2+K3+K4)

[0054] Wherein: P: MFe grade; K: single ore blending shovel ore quantity; KM: comprehensive grindability index; KX: comprehensive selectability index; S: comprehensive sulfur index; G: dry separation tailing rate

[0055] P1: MFe grade of ore block 1; KM1: comprehensive grindability index of ore block 1; KM1: comprehensive selectability index of ore block 1; S1: comprehensive sulfur index of ore block 1; G1: dilution of ore block 1, i.e. dry separation tailing rate.

[0056] 7, The sulfur organization ore blending principle is: first calculate each index according to the ore blending principle, then organize the ore, and give priority to ensuring the sulfur content and MFe grade when there is a special unqualified index to ensure the ore quantity. Special control measures are developed for the sulfur index:

[0057] (1) Strictly according to the ore blending principle of "sulfur > selectability > grindability > MFe grade > dry separation tailing rate" to organize the ore, and the dispatcher should not adjust the shovel position to organize the ore blending.

[0058] 2. The organization of the ore under the mine must be in accordance with the sulfur content of the medium pore map, and the ore explosion pile that has not been out of the map must not be privately organized to organize the ore. After the sulfur content index is out of the map, participate in ore blending.

[0059] 6. The medium pore map is out within one day after the test results are out, to ensure the accuracy of ore blending.

[0060] 7. The detailed information is sent to the dispatching room within one day after the medium pore map is out, and the dispatcher is required to be familiar with the medium pore map for mining and correspond to the site to ensure the accuracy of mining.

[0061] 8. Strictly control the high-sulfur explosion pile, organize the ore with the ore blending car group, stop the ore after one shift (8 hours, three shifts a day), and look at the test results of the beneficiation. If the results are within the controllable range, the ore can continue to be organized. If the test results are high, stop the high-sulfur explosion pile immediately. In the subsequent production organization, on the one hand, the sampling and testing plan of the high-sulfur area is refined, and on the other hand, the emergency plan is adjusted and started:

[0062] 1. Organize high-sulfur ore blending operation with one car per hour, stop operation after one day of mining, and wait for the final output concentrate sulfur results;

[0063] 2. During the period of high-sulfur ore into the well, the beneficiation process does not switch the bin, which is convenient for calculating the bin ore drawing situation and reducing the impact on the high-sulfur ore selection index;

[0064] 3. During the period of high-sulfur ore into the well, the final output concentrate sulfur test frequency is adjusted from 1 time / 6h to 1 time / 2h, which is convenient for timely discovering the impact of high-sulfur ore into the well.

[0065] 9. When the sulfur content appears abnormal, the mining shovel position must be adjusted immediately, the cause is found on site and analyzed.

[0066] 10. After adopting the desulfurization production process method of "mining and ore blending" + "stage grinding and stage separation" for low-sulfur lean magnetite ore, the sulfur content of the overflow product of the first stage grinding and classification is between 0.1% and 0.3%, and after the second and third stage grinding and four times of magnetic separation, the sulfur throw-off rate of the raw ore is about 65%, and the final concentrate sulfur content is less than 0.05% per 6 hours.

[0067] The mining and ore blending is based on the test results of the medium pore sample in the laboratory, and the sulfur, grade, grindability, and selectability indexes are marked on the medium pore map. Then, according to the ore reserves of each area, the ore blending plan for one week is calculated, and the hourly ore into the well of each mining area is refined. The ore blending principle is: sulfur content less than 0.05%, grindability greater than 0.8%, and selectability greater than 0.9; magnetic iron grade greater than the monthly budget (normal is about 24%), and daily local adjustment is made according to the hourly production index of the next beneficiation process.

[0068] The concentrate is sampled every hour for the final output concentrate, and the comprehensive test is conducted for 6 hours, which is normally below 0.03%, if it is higher than 0.035%, the test frequency is increased, and if it is more than 0.04%, the mining scheduling is immediately adjusted.

[0069] Embodiment

[0070] In the production of a certain iron mine, according to the ore reserves in the stope in mid-March, the ore production organization is carried out according to the stope sulfur allocation scheme. The specific steps are as follows:

[0071] 1) The then in-use blast heap area is circled, and the corresponding ore quantity, sulfur content, grade, grindable, washable, and monthly budget in the hole map of the area are determined.

[0072] 2) According to the ore allocation principle and calculation formula in the technical concept, the following is calculated (3# chute ore, 4# chute standby).

[0073]

[0074] 3) The strip area of the high-sulfur blast area 33# of the stope is carried out by the raw ore administrator and the day shift scheduling, and the excavation area positioning is marked with flags on site.

[0075] 4) The raw ore administrator formulates the ore allocation scheme (the number of ore allocation cars for each ore point); the on-site scheduling is organized according to the ore allocation scheme, and the indoor scheduling checks the actual ore quantity and the difference between the ore allocation scheme every two hours, and the hourly deviation is less than 1 car.

[0076] 5) When the high-sulfur ore is put on site, the mine scheduling is warned 3 days in advance, and the beneficiation system is notified to make corresponding adjustment.

[0077] 6) The main pump output concentrate sulfur content is implemented by the on-site scheduling every day, the sulfur content change is analyzed, the abnormality is found out in time, the internal ore allocation is adjusted, and the high-sulfur ore is preliminarily reduced by half.

[0078] 7) The high-sulfur ore is put into the well according to the principle of small batch and multiple batches, and the high-sulfur ore is put into the well every 3-4 days, so as to prevent the continuous abnormality of the output concentrate.

[0079] The above embodiment shows that the sulfur grade of the main pump output concentrate in March meets the user's demand (sulfur <0.04), not only meets the ore mining and promotion of the key parts of the stope, but also stabilizes the output product quality, and creates economic benefits of about 500,000 yuan.

[0080] The above only describes the specific embodiments of the present application, but the structural features of the scope of protection of the present application are not limited to this, any changes or modifications made by those skilled in the art in the field of the present application are covered by the patent scope of the present application.

Claims

1. A process for desulphurization of low sulphur lean magnetite, the process comprising: The method comprises the following steps: ​ Step one: sampling the holes in the mining area, testing the raw ore sulfur index, and at the same time, carrying out stage grinding-stage separation and desulfurization test on the raw ore, and testing the concentrate S index, if the test result is that the concentrate sulfur is lower than the raw ore sulfur, the normal grinding and separation process is carried out, if the concentrate sulfur is higher than the raw ore sulfur, the following steps are carried out; Step two: organizing stage grinding-stage separation and desulfurization test to determine that the upper limit of the sulfur content of the raw ore in the mining area is 0.12% or less; Step three: determining the organization details, process correction and monitoring details, and abnormal early warning mechanism of the sulfur allocation in the mining area; Step four: according to the primary and secondary factors of the index, the mining and ore allocation index and its order are determined in turn as follows: sulfur index>selectable index>grindable index>MFe grade>dry separation tailing rate; Step five: the target of the mining and ore allocation index and the ore allocation method are determined, which are as follows: 1) monthly ore loss rate is less than or equal to 5%, 2) the MFe grade of the raw ore entering the mill is within the range of the monthly plan grade ± 1% in the daily qualified interval, 3) the MFe grade of the raw ore entering the mill is within the range of the monthly plan grade ± 0.25% in the monthly qualified interval, 4) daily ore allocation index: 1.1≥KM≥0.87, 1.2≥KX≥0.9, S content is less than or equal to 0.08%, 5) monthly dry separation tailing rate is less than or equal to 14%, and single-day dry separation tailing rate is less than or equal to 18%, 6) powder ore should not be concentrated into the shaft to ensure the safe operation of the shaft; Step six: the ore allocation principle is: first allocate MFe grade, and then calculate other indexes when MFe grade is qualified, when a certain index is unqualified, adjust the ore quantity to ensure that all indexes are qualified, and when all indexes are qualified, allocate ore according to the scheme, when there is a conflict between indexes, ensure that the sulfur content is qualified first, and when other indexes are unqualified, warn the ore dressing process, and the calculation method is: P=(P1*K1+P2*K2+P3*K3+P4*K4) / (K1+K2+K3+K4) KM=(KM1*K1+KM2*K2+KM3*K3+KM4*K4) / (K1+K2+K3+K4) KX=(KX1*K1+KX2*K2+KX3*K3+KX4*K4) / (K1+K2+K3+K4) S=(S1*K1+S2*K2+S3*K3+S4*K4) / (K1+K2+K3+K4) G=(G1*K1+G2*K2+G3*K3+G4*K4) / (K1+K2+K3+K4) Wherein: P: MFe grade, KM: comprehensive grindable index, KX: comprehensive selectable index, S: comprehensive sulfur index, G: dry separation tailing rate, P1: MFe grade of ore block 1, KM1: grindable index of ore block 1, KX1: selectable index of ore block 1, S1: sulfur index of ore block 1, G1: dry separation tailing rate of ore block 1, K1: ore quantity of ore block 1; P2: MFe grade of ore block 2, KM2: grindable index of ore block 2, KX2: selectable index of ore block 2, S2: sulfur index of ore block 2, G2: dry separation tailing rate of ore block 2, K2: ore quantity of ore block 2; P3: MFe grade of ore block 3, KM3: grindability index of ore block 3, KX3: washability index of ore block 3, S3: sulfur index of ore block 3, G3: dry separation tailing rate of ore block 3, K3: ore loss of ore block 3; P4: MFe grade of ore block 4, KM4: grindability index of ore block 4, KX4: washability index of ore block 4, S4: sulfur index of ore block 4, G4: dry separation tailing rate of ore block 4, K4: ore loss of ore block 4; Step seven: sulfur organization ore blending principle: first according to the ore blending principle to calculate each index, all qualified after organization ore, have special unqualified first guarantee sulfur content and MFe grade qualified, guarantee ore loss, for sulfur index to develop control measures.

2. A process for desulphurization of low sulphur lean magnetite ore as claimed in claim 1 wherein: The control measures for sulfur index in step seven are as follows: 1) strictly according to the ore blending principle of "sulfur index > washability index > grindability index > MFe grade > dry separation tailing rate" to organize ore; 2) when organizing ore, according to the sulfur content on the middle hole diagram to organize ore blending; 3) the middle hole diagram is output within one day after the test result is obtained, to ensure the accuracy of ore blending; 4) strictly control high sulfur heap, organize ore with ore blending car group, look at the beneficiation test result, if the result is in the controllable range, that is, S content ≤0.05%, the ore can continue to be organized; if the test result is high, that is, the S content of concentrate powder >0.05%, stop the high sulfur heap immediately, and in the following production organization: ① organize high sulfur ore blending operation with one car per hour, that is, 115-135 tons, stop the operation after one day of ore, and wait for the final output of sulfur in concentrate, ② during the period of high sulfur ore into the well, the ore dressing process does not switch the bin, ③ during the period of high sulfur ore into the well, the final output of sulfur in concentrate is adjusted from 1 time / 6h to 1 time / 2h; 5) when the sulfur content is abnormal, that is, S content >0.05%, immediately adjust the shovel position to change the original ore blending scheme, that is, change the ore strip, and move or change the digging direction of the shovel position causing abnormal S content; 6) after adopting the "mining and ore blending" + "stage grinding and stage separation" desulfurization production process for low sulfur and lean magnetite, the sulfur content of the overflow product of the first stage grinding is between 0.1%-0.3%, after the second and third stage grinding and four times of magnetic separation, the sulfur throw-off rate of the raw ore is 65-80%, and the final sulfur content of the concentrate is less than 0.05% every 6 hours.

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