A process for the complete combustion of sulphur ores in a fluidized bed furnace

Abstract

The present application relates to the technical field of mineral processing and metallurgy, and particularly relates to a processing technology for full combustion of sulfur ore in a fluidized bed furnace, which comprises the following steps: after the pyrite is crushed, the pyrite is screened and then compounded, and then the pyrite is floated with a high-efficiency inhibitor to obtain pretreated pyrite powder; the pretreated pyrite powder is then added into the fluidized bed furnace, is leveled and then is fully combusted to obtain furnace gas and furnace slag; the high-efficiency inhibitor is obtained by mixing sodium hyposulfite, sodium mercaptoacetate, sodium humate and a buffer; wherein the furnace temperature during the full combustion is 910-930 DEG C, the combustion duration is 4-5 h, and the oxygen concentration at the outlet of the fluidized bed furnace is 2.5%-3.0%. The specific particle size and high-quality combination roasting process of the pretreated pyrite powder make the present application have higher burning-out rate, higher iron grade of the furnace slag and longer service life of the circulating pump compared with the prior art, and the application prospect is also wider.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral processing and metallurgy, and particularly relates to a processing technology for full combustion of sulfur ore in a fluidized bed furnace. BACKGROUND

[0002] Pyrite is a general term for three kinds of sulfur-containing minerals, namely pyrite, marcasite and pyrrhotite. It is often golden yellow, brass color, sometimes yellow-green, has bright metallic luster, and the streak is green-black or brown-black. It is mostly in the form of block, granular or crystalline, and the crystal structure is mostly cubic. The main component of pyrite is ferrous sulfide, and the hardness is 6.0-6.5. It can be burned in air, produces blue flame, and emits a pungent odor. Pyrite can be used to produce sulfuric acid through roasting to generate sulfur dioxide, catalytic oxidation and hydration reaction. The tail gas generated during roasting can also be used to produce sulfur yellow, and the high-grade roasted slag can be directly used for iron and steel smelting. The low-grade roasted slag can be used for iron smelting or cement batching after treatment. Therefore, the roasting process is particularly important in the treatment of pyrite.

[0003] If the pyrite cannot be burned in the fluidized bed furnace, not only the burning rate will be reduced, but also the grade of the roasted slag will be reduced, and the yield of original acid mist and gaseous sulfur in the furnace gas will be increased. However, the prior art method still lacks attention to this problem. For example, patent document CN102586618A discloses a smelting process of pyrite. The smelting process is to smelt pyrite by using oxidation smelting method, and generate rich noble metal matte, high-iron molten slag and high-temperature flue gas containing sulfur dioxide after smelting. The matte is discharged and settled at the bottom of the hearth, and the matte is separated from the high-iron molten slag. The high-iron molten slag is smelted by using a reduction smelting pool smelting furnace to generate pig iron. The discharged matte is used for recovering noble metal, and the discharged high-temperature flue gas is used for waste heat recovery and acid production. The invention focuses on achieving energy saving effect through the oxidation reaction heat of pyrite itself and the sensible heat of molten slag. However, the problems of burning rate and slag grade are ignored.

[0004] Therefore, according to the related technology in the above, it is urgent to develop a processing technology for full combustion of sulfur ore in a fluidized bed furnace. SUMMARY

[0005] In view of this, the purpose of the present application is to provide a processing technology for full combustion of sulfur ore in a fluidized bed furnace, so as to solve the problems of low burning rate of pyrite and low iron grade in the slag in the prior art.

[0006] Based on the above purpose, the present application provides a processing technology for full combustion of sulfur ore in a fluidized bed furnace.

[0007] A processing technology for full combustion of sulfur ore in a fluidized bed furnace, comprising the following steps:

[0008] Step S1: After the pyrite is crushed and sieved, a compounded pyrite powder is obtained after compounding.

[0009] Step S2: using high-efficiency inhibitors to float the compounded pyrite powder to obtain pretreated pyrite powder;

[0010] Step S3: adding the treated pyrite powder into the fluidized bed furnace, laying flat and then fully burning to obtain furnace gas and furnace slag;

[0011] The high-efficiency inhibitor in step S2 is obtained by mixing sodium hyposulfite, sodium mercaptoacetate, sodium humate and a buffer;

[0012] In step S3, the furnace temperature during the full combustion treatment is 910-930℃, the combustion time during the full combustion treatment is 4-5h, the oxygen concentration at the outlet of the fluidized bed furnace during the full combustion treatment is 2.5%-3.0%, the negative pressure at the outlet of the fluidized bed furnace during the full combustion treatment is -0.6kPa--0.4kPa, and the furnace bottom pressure of the fluidized bed furnace during the full combustion treatment is 16.0kPa-17.0kPa.

[0013] Preferably, the fluidized bed furnace in step S3 is a modified fluidized bed furnace, and the modification method is to first increase the cavity of the fluidized bed furnace by 4000-4390mm, then change the flue port from L-shaped to oblique square-shaped, and finally add two Φ240mm supplementary air holes on the oblique square-shaped flue port. The modified fluidized bed furnace has a furnace bottom area of 54m 2 , a furnace bottom air volume of 21000Nm 3 / h, a flue gas residence time of 21-23s, and a roasting intensity of 12t·m -2 ·d -1 .

[0014] Preferably, the screening process in step S1 is as follows:

[0015] Firstly, screen with a sieve with a pore size of 150μm, then screen with a sieve with a pore size of 48μm, and finally screen with a sieve with a pore size of 38μm to obtain pyrite powder with a particle size of 48-150μm, pyrite powder with a particle size of 38-48μm and pyrite powder with a particle size of 0-38μm.

[0016] Preferably, the compounded pyrite powder is obtained by mixing pyrite powder with a particle size of 48-150μm, pyrite powder with a particle size of 38-48μm and pyrite powder with a particle size of 0-38μm in a mass ratio of 1-2:14-18:80.

[0017] Preferably, the flotation process in step S2 is as follows:

[0018] Step A1: add the compounded pyrite powder into water, stir until uniform, then add the high-efficiency inhibitor and maintain the pH value of the slurry at 9-10, and then add the collector and the foaming agent in sequence for 3-6min flotation to obtain foam product 1 and tailings 1;

[0019] Step A2: adding high-efficiency depressant into tailings 1 and maintaining the pH value of the slurry at 9-10, then adding collector and frother in turn for 1-3 min of scavenging to obtain froth product 2 and tailings 2; the scavenging operation further weakens the non-selective adsorption mass transfer of the collector on the surface of arsenopyrite by precisely controlling the dosage of reagents and reducing the flotation time, thereby improving the recovery rate and quality of the froth product;

[0020] Step A3: mixing the froth product 1 and the froth product 2, then adding high-efficiency depressant, and obtaining froth product 3 and tailings 3 after 1-3 min of cleaning;

[0021] Step A4: mixing the tailings 2 and the tailings 3 and drying to obtain pretreated pyrite powder.

[0022] Preferably, the mass ratio of sodium hydrosulfite, sodium mercaptoacetate, sodium humate, and buffer is 2-3: 1: 1: 1-2.

[0023] Preferably, the buffer is any one or more of sodium phosphate, sodium carbonate, and sodium borate.

[0024] The collector is any one or more of sodium ethyl xanthate, sodium butyl xanthate, and sodium dibutyl dithiophosphate.

[0025] The frother is any one or more of pinol oil, methyl isobutyl carbinol, and camphor oil.

[0026] Preferably, the mass ratio of water to the compounded pyrite powder in step A1 is 100: 15-25.

[0027] The dosage of the high-efficiency depressant in step A1 is 900-1100 g / t.

[0028] The dosage of the collector in step A1 is 100-200 g / t.

[0029] The dosage of the frother in step A1 is 30-60 g / t.

[0030] Preferably, the dosage of the high-efficiency depressant in step A2 is 300-600 g / t.

[0031] The dosage of the collector in step A2 is 20-60 g / t.

[0032] The dosage of the frother in step A2 is 6-20 g / t.

[0033] Preferably, the dosage of the high-efficiency depressant in step A3 is 300-900 g / t.

[0034] Preferably, the thickness of the pre-processed pyrite powder in the boiling furnace after the flattening in step S3 is 550-600 mm.

[0035] Advantages of the present application:

[0036] The present application provides a processing technology for full combustion of sulfur ore in a boiling furnace. The present application improves the residence time of pyrite combustion in the furnace and prolongs the residence time of furnace gas by modifying the boiling furnace. The full combustion of pyrite powder is achieved by roasting in the modified boiling furnace with specific process, which not only improves the roasting rate of pyrite and the iron grade of the roasted slag, but also reduces the total sulfur content of the roasted slag, reduces the generation of original acid mist and gaseous sulfur in the furnace gas, reduces the generation of sublimed sulfur in the purification section dynamic wave packed tower, thereby prolonging the resistance rising period, stabilizing the system resistance, prolonging the service life of the circulating pump of the dynamic wave and packed tower, preventing the occurrence of pump leakage, and improving the acid production of the device.

[0037] The present application performs screening treatment before flotation and compounding according to a specific ratio, which improves the flotation efficiency and controls the volume expansion during the roasting process, thereby controlling the slag volume within the range that the slag drum can withstand.

[0038] The special high-efficiency inhibitor added in the flotation process of the present application selectively maximizes the inhibition of group adsorption mass transfer on the mineral surface, while weakening the oxidation mass transfer on the mineral surface, so that the mineral surface still has active areas and sites that can adsorb collectors, thereby making the floated pyrite more precise.

[0039] The present application improves the feed quality of the boiling furnace, thereby further improving the acid production and the total iron content in the slag. Therefore, compared with the prior art, the pyrite processing technology of the present application not only has high roasting rate and high iron grade of the slag, but also has a more extensive application prospect. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions and advantages of the present application clearer and more explicit, the present application is further described in detail below with specific examples.

[0041] Example 1: A processing technology for full combustion of sulfur ore in a boiling furnace is as follows:

[0042] The method for modifying the boiling furnace is to first increase the cavity of the boiling furnace by 4000 mm, then change the flue port from L-shaped to oblique square-shaped, and finally add two Φ240 mm supplementary air holes on the oblique square-shaped flue port. The bottom area of the modified boiling furnace is 54 m 2 , the bottom air volume is 21000 Nm 3 / h, the flue gas residence time is 21 s, and the roasting intensity is 12 t·m-2 ·d -1 .

[0043] Example 2: A processing technology for full combustion of a sulfur ore in a fluidized bed furnace is as follows:

[0044] The method for modifying the fluidized bed furnace is to first increase the cavity of the fluidized bed furnace by 4390mm, then change the flue port from L-shaped to oblique square-shaped, and finally add two Φ240mm supplementary air holes to the oblique square-shaped flue port. After modification, the furnace bottom area of the fluidized bed furnace is 54m 2 , the furnace bottom air volume is 21000Nm 3 / h, the flue gas residence time is 23s, and the roasting intensity is 12t·m -2 ·d -1 .

[0045] Example 3: A processing technology for full combustion of a sulfur ore in a fluidized bed furnace is as follows:

[0046] S1: After crushing 100t of pyrite, first screen with a screen size of 150μm, then screen with a screen size of 48μm, and then screen with a screen size of 38μm, to obtain pyrite powder with a particle size of 48-150μm, pyrite powder with a particle size of 38-48μm, and pyrite powder with a particle size of 0-38μm.

[0047] S2: Mix 1t of pyrite powder with a particle size of 48-150μm, 14t of pyrite powder with a particle size of 38-48μm, and 80t of pyrite powder with a particle size of 0-38μm to obtain compounded pyrite powder;

[0048] S3: Mix 36kg of sodium hydrosulfite, 18kg of sodium mercaptoacetate, 18kg of sodium humate, and 18kg of sodium phosphate to obtain a high-efficiency inhibitor.

[0049] S4: Add the compounded pyrite powder to water at a mass ratio of 100:15, stir uniformly, then add the high-efficiency inhibitor and maintain the pH value of the ore slurry at 9-10, and then sequentially add sodium ethyl xanthate and pine oil for 3min of flotation to obtain foam product 1 and tailings 1; wherein the amount of high-efficiency inhibitor is 900g / t; the amount of sodium ethyl xanthate is 100g / t; and the amount of pine oil is 30g / t.

[0050] S5: Add the high-efficiency inhibitor to the tailings 1 and maintain the pH value of the ore slurry at 9-10, then sequentially add sodium ethyl xanthate and pine oil for 1min of scavenging to obtain foam product 2 and tailings 2; wherein the amount of high-efficiency inhibitor is 300g / t; the amount of sodium ethyl xanthate is 20g / t; and the amount of pine oil is 6g / t.

[0051] S6: Mix the froth product 1 and the froth product 2, then add the high-efficiency inhibitor to obtain the froth product 3 and the tailings 3 after 1 min of selection; the amount of the high-efficiency inhibitor is 300 g / t.

[0052] S7: Mix the tailings 2 and the tailings 3, then dry to obtain the pretreated pyrite powder.

[0053] S8: Put the pretreated pyrite powder into the fluidized bed furnace, lay flat, and then fully burn to obtain the furnace gas and the furnace slag; the thickness of the pretreated pyrite powder in the fluidized bed furnace after laying flat is 550 mm; the furnace temperature during the full combustion treatment is 910℃, the combustion time is 4 h, the oxygen concentration at the outlet of the fluidized bed furnace is 2.5%, the negative pressure at the outlet of the fluidized bed furnace is -0.4 kPa, and the pressure at the bottom of the fluidized bed furnace is 16.0 kPa.

[0054] Example 4: A processing technology for fully burning a pyrite in a fluidized bed furnace is as follows:

[0055] S1: After crushing the pyrite, screen it with a sieve with a pore size of 150 μm, then screen it with a sieve with a pore size of 48 μm, and then screen it with a sieve with a pore size of 38 μm to obtain pyrite powder with a particle size of 48-150 μm, pyrite powder with a particle size of 38-48 μm, and pyrite powder with a particle size of 0-38 μm.

[0056] S2: Mix 1.5 t of pyrite powder with a particle size of 48-150 μm, 15 t of pyrite powder with a particle size of 38-48 μm, and 80 t of pyrite powder with a particle size of 0-38 μm to obtain the compounded pyrite powder.

[0057] S3: Mix 39.65 kg of sodium hydrosulfite, 17.25 kg of sodium mercaptoacetate, 17.25 kg of sodium humate, and 25.86 kg of sodium carbonate to obtain the high-efficiency inhibitor.

[0058] S4: Add the compounded pyrite powder in water at a mass ratio of 100:18, stir uniformly, then add the high-efficiency inhibitor and maintain the pH value of the slurry at 9-10, and then add sodium dibutyl dithiophosphate and camphor oil in sequence for 4 min of flotation to obtain the froth product 1 and the tailings 1; the amount of the high-efficiency inhibitor is 1000 g / t; the amount of the sodium dibutyl dithiophosphate is 130 g / t; and the amount of the camphor oil is 40 g / t.

[0059] S5: Add the high-efficiency inhibitor to the tailings 1 and maintain the pH value of the slurry at 9-10, then add sodium butyl xanthate and methyl isobutyl carbinol in sequence for 2 min of scavenging to obtain the froth product 2 and the tailings 2; the amount of the high-efficiency inhibitor is 400 g / t; the amount of the sodium butyl xanthate is 30 g / t; and the amount of the methyl isobutyl carbinol is 10 g / t.

[0060] S6: mixing the froth product 1 and the froth product 2, then adding the high-efficiency depressant to obtain the froth product 3 and the tailings 3 after 2 min of selection; the amount of the high-efficiency depressant is 400 g / t.

[0061] S7: mixing the tailings 2 and the tailings 3 and then drying to obtain the pretreated pyrite powder.

[0062] S8: adding the pretreated pyrite powder into the fluidized bed furnace, laying flat and then performing the sufficient combustion treatment to obtain the furnace gas and the furnace slag; wherein the thickness of the pretreated pyrite powder in the fluidized bed furnace after laying flat is 560 mm; the furnace temperature during the sufficient combustion treatment is 915℃, the combustion duration is 4.4 h, the oxygen concentration at the outlet of the fluidized bed furnace is 2.7%, the negative pressure at the outlet of the fluidized bed furnace is -0.5 kPa, and the pressure at the bottom of the fluidized bed furnace is 16.3 kPa.

[0063] Example 5: a processing technology of the pyrite in the fluidized bed furnace for sufficient combustion is as follows:

[0064] S1: after crushing the pyrite, sieving with a sieve with a pore size of 150 μm, then sieving with a sieve with a pore size of 48 μm, and then sieving with a sieve with a pore size of 38 μm to obtain the pyrite powder with a particle size of 48-150 μm, the pyrite powder with a particle size of 38-48 μm, and the pyrite powder with a particle size of 0-38 μm.

[0065] S2: mixing 1.7 t of the pyrite powder with a particle size of 48-150 μm, 16 t of the pyrite powder with a particle size of 38-48 μm, and 80 t of the pyrite powder with a particle size of 0-38 μm to obtain the compounded pyrite powder.

[0066] S3: mixing 44.3 kg of sodium dithionite, 16.4 kg of sodium mercaptoacetate, 16.4 kg of sodium humate, 16.4 kg of sodium carbonate, and 11.5 kg of sodium borate to obtain the high-efficiency depressant.

[0067] S4: adding the compounded pyrite powder in water at a mass ratio of 100:22, stirring uniformly, then adding the high-efficiency depressant and maintaining the pH value of the slurry at 9-10, and then adding sodium ethyl xanthate, sodium butyl xanthate, and pine oil, methyl isobutyl carbinol in sequence for 5 min of flotation to obtain the froth product 1 and the tailings 1; wherein the amount of the high-efficiency depressant is 1050 g / t; the amount of sodium ethyl xanthate is 100 g / t; the amount of sodium butyl xanthate is 70 g / t; the amount of pine oil is 30 g / t; and the amount of methyl isobutyl carbinol is 20 g / t.

[0068] S5: adding high-efficiency depressant into the tailings 1 and maintaining the pH value of the ore pulp at 9-10, then adding sodium butyl xanthate, sodium dibutyl dithiophosphate and methyl isobutyl carbinol, camphor oil in turn for 2 min of scavenging to obtain the froth product 2 and the tailings 2; wherein, the dosage of the high-efficiency depressant is 500 g / t; the dosage of sodium butyl xanthate is 30 g / t; the dosage of sodium dibutyl dithiophosphate is 20 g / t; the dosage of methyl isobutyl carbinol is 9 g / t, and the dosage of camphor oil is 9 g / t.

[0069] S6: mixing the froth product 1 and the froth product 2, then adding high-efficiency depressant to obtain the froth product 3 and the tailings 3 after cleaning for 2 min; the dosage of the high-efficiency depressant is 800 g / t.

[0070] S7: mixing the tailings 2 and the tailings 3 and drying to obtain the pretreated pyrite powder.

[0071] S8: adding the pretreated pyrite powder into the fluidized bed furnace, laying flat and then performing sufficient combustion treatment to obtain the furnace gas and the furnace slag; wherein, the thickness of the pretreated pyrite powder in the fluidized bed furnace after laying flat is 580 mm; the furnace temperature during the sufficient combustion treatment is 925℃, the combustion time is 4.8 h, the oxygen concentration at the outlet of the fluidized bed furnace is 2.8%, the negative pressure at the outlet of the fluidized bed furnace is -0.55 kPa, and the pressure at the bottom of the fluidized bed furnace is 16.8 kPa.

[0072] Example 6: a processing technology of sufficient combustion of a sulfur ore in a fluidized bed furnace is as follows:

[0073] S1: after crushing the pyrite, first screening with a screen mesh with a pore size of 150 μm, then screening with a screen mesh with a pore size of 48 μm, and then screening with a screen mesh with a pore size of 38 μm to obtain pyrite powder with a particle size of 48-150 μm, pyrite powder with a particle size of 38-48 μm and pyrite powder with a particle size of 0-38 μm.

[0074] S2: mixing 2 t of pyrite powder with a particle size of 48-150 μm, 18 t of pyrite powder with a particle size of 38-48 μm and 80 t of pyrite powder with a particle size of 0-38 μm to obtain the compounded pyrite powder.

[0075] S3: mixing 47.15 kg of sodium dithionite, 15.71 kg of sodium mercaptoacetate, 15.71 kg of sodium humate, 15.71 kg of sodium phosphate and 15.71 kg of sodium borate to obtain the high-efficiency depressant.

[0076] S4: adding the compound pyrite powder in water with a mass ratio of 100:25, adding high efficiency inhibitor after stirring uniformly, maintaining the pH value of the slurry at 9-10, and then adding ethyl sodium xanthate, butyl sodium xanthate, sodium dibutyl dithiophosphate, and pine oil, methyl isobutyl carbinol, and camphor oil in sequence for 6 min flotation to obtain foam product 1 and tailings 1; the amount of the high efficiency inhibitor is 1100 g / t; the amount of ethyl sodium xanthate is 100 g / t; the amount of butyl sodium xanthate is 50 g / t; the amount of sodium dibutyl dithiophosphate is 50 g / t; the amount of pine oil is 20 g / t; the amount of methyl isobutyl carbinol is 20 g / t; and the amount of camphor oil is 20 g / t.

[0077] S5: adding high efficiency inhibitor to the tailings 1 and maintaining the pH value of the slurry at 9-10, and then adding ethyl sodium xanthate, butyl sodium xanthate, sodium dibutyl dithiophosphate, and pine oil, methyl isobutyl carbinol, and camphor oil in sequence for 3 min scavenging to obtain foam product 2 and tailings 2; the amount of the high efficiency inhibitor is 600 g / t; the amount of ethyl sodium xanthate is 20 g / t; the amount of butyl sodium xanthate is 20 g / t; the amount of sodium dibutyl dithiophosphate is 20 g / t; the amount of pine oil is 10 g / t; the amount of methyl isobutyl carbinol is 5 g / t; and the amount of camphor oil is 5 g / t.

[0078] S6: mixing the foam product 1 and the foam product 2, and then adding high efficiency inhibitor to obtain foam product 3 and tailings 3 after cleaning for 3 min; the amount of the high efficiency inhibitor is 900 g / t.

[0079] S7: mixing the tailings 2 and the tailings 3 and drying to obtain pretreated pyrite powder.

[0080] S8: adding the pretreated pyrite powder into the fluidized bed furnace, and then performing sufficient combustion treatment after leveling to obtain furnace gas and furnace slag; the thickness of the pretreated pyrite powder in the fluidized bed furnace after leveling is 600 mm; the furnace temperature during the sufficient combustion treatment is 930 ℃, the combustion time is 5 h, the oxygen concentration at the outlet of the fluidized bed furnace is 3.0%, the negative pressure at the outlet of the fluidized bed furnace is -0.6 kPa, and the pressure at the bottom of the fluidized bed furnace is 17.0 kPa.

[0081] Comparative Example 1

[0082] The fluidized bed furnace in this comparative example is not modified compared with Example 3, and the rest of the steps and parameters are the same. The comparative example will not be repeated here. Finally, the furnace slag is obtained; the area of the bottom of the modified fluidized bed furnace is 54 m 2 , the air volume at the bottom of the fluidized bed furnace is 20000 Nm 3 / h, the flue gas residence time is 18 s, and the roasting intensity is 11.1 t·m -2 ·d -1 .

[0083] Comparative Example 2:

[0084] The present comparative example is compared with Example 3 only replacing the step of mixing pyrite powder with particle size of 48-150 μm, 38-48 μm and 0-38 μm in a mass ratio of 1.5:15:80 in the preparation of compounded pyrite powder with the step of mixing pyrite powder with particle size of 38-150 μm and 0-38 μm in a mass ratio of 5:91.5, and the rest of the steps and parameters are the same, which will not be repeated here. The final slag is obtained.

[0085] Comparative Example 3:

[0086] The present comparative example is compared with Example 1 only replacing sodium dithionite and sodium mercaptoacetate with sodium humate, and the rest of the steps and parameters are the same, which will not be repeated here. The final slag is obtained.

[0087] Comparative Example 4:

[0088] The present comparative example is compared with Example 1 only replacing sodium humate with sodium dithionite and sodium mercaptoacetate, and the rest of the steps and parameters are the same, which will not be repeated here. The final slag is obtained.

[0089] Comparative Example 5:

[0090] The present comparative example is compared with Example 1 only replacing the tailings 2 and 3 dried in the preparation of pretreated pyrite powder with tailings 1, and the rest of the steps and parameters are the same, which will not be repeated here. The final slag is obtained.

[0091] Comparative Example 6:

[0092] The present comparative example is compared with Example 1 only replacing the thickness of the pretreated pyrite powder in the fluidized bed boiler after leveling from 550 mm to 700 mm, and the rest of the steps and parameters are the same, which will not be repeated here. The final slag is obtained.

[0093] Performance test:

[0094] Determination of effective sulfur content of slag:

[0095] A 0.12% methyl red alcohol solution and a 0.08% methylene blue alcohol solution were mixed in a volume ratio of 1:1 to obtain a mixed indicator. 2 g of the slag was uniformly spread on a petri dish, dried at 105°C for 1 h, ground to 100 mesh, dried at 105°C for another 0.5 h, and then uniformly spread on a porcelain boat. The electric furnace was kept at a high temperature, 20 mL of a 3% hydrogen peroxide solution was injected into the porcelain boat through a separatory funnel under a vacuum, 3-4 drops of the mixed indicator and 80 mL of distilled water were added, and the stopcock was closed. A 0.1% sodium hydroxide solution was added to the burette to neutralize the absorption solution, and the sodium hydroxide solution was added to the zero mark of the burette. When the temperature of the electric furnace reached 860°C, the porcelain boat containing the sample in the drying oven was taken out and inserted into the center of the combustion tube under a vacuum, and the end of the tube was tightly plugged. The sample was burned for 15 min. The burning was titrated with the 0.1% sodium hydroxide solution until the color of the absorption solution changed from purple red to brown green, which was the end point of the titration. Then the absorption was continued for 5 min until the absorption solution did not change color, indicating that the burning and absorption were completed. After the burning was completed, the washing branch was washed for more than three times, each time with about 5 mL of the 0.1% sodium hydroxide solution, and the absorption solution was discarded. The washing was repeated for 3 times. The total amount of the sodium hydroxide solution was recorded, and the effective sulfur content in the slag was calculated according to Formula 1. The effective sulfur content (%) of the slag obtained by firing according to Examples 3-6 and Comparative Examples 1-6 was determined according to the method.

[0096] Formula 1: V is the amount of the 0.1% sodium hydroxide solution, mL.

[0097] In Formula 1, V is the amount of the 0.1% sodium hydroxide solution, mL.

[0098] Burning rate:

[0099] A 0.12% methyl red alcohol solution and a 0.08% methylene blue alcohol solution were mixed in a volume ratio of 1:1 to obtain a mixed indicator. 2 g of pyrite was uniformly spread on a petri dish, dried at 105°C for 1 h, ground to 100 mesh, dried at 105°C for another half hour, and then uniformly spread on a porcelain boat. An electric furnace was turned on and kept at a high temperature. Under vacuum, 20 mL of a 3% hydrogen peroxide solution was injected into a separatory funnel, followed by 3-4 drops of the mixed indicator and 80 mL of distilled water, and then the stopcock was closed. A 0.1% sodium hydroxide solution was added to the absorption solution using a burette, and then the sodium hydroxide solution was added to the zero mark of the burette. When the temperature of the electric furnace reached 860°C, the porcelain boat containing the sample in the drying oven was taken out and inserted into the center of the combustion tube under continuous vacuum, and the end of the tube was tightly plugged. The sample was combusted for 15 min. The combustion was titrated with the 0.1% sodium hydroxide solution until the color of the absorption solution changed completely from purple red to brown green, which was the end point of the titration. Then, the absorption was continued for 5 min until the absorption solution did not change color, indicating that the combustion and absorption were completed. After the combustion was completed, the washing branch was washed for more than three times, each time using about 5 mL. The absorption solution was discarded, and the washing was repeated three times using the 0.1% sodium hydroxide solution. The total amount of the sodium hydroxide solution was recorded, and the effective sulfur content of the pyrite was calculated according to Formula 1. The burnout rate (%) of Examples 3-6 and Comparative Examples 1-6 was calculated according to Formula 2:

[0100] Formula 2:

[0101] Determination of total iron content in slag:

[0102] 0.50 g of slag was weighed into a 250 mL triangular flask, 0.5 g of sodium fluoride and 50 mL of concentrated hydrochloric acid were added, and the mixture was heated and dissolved on a heating plate. The solution was dissolved to about 10 mL, and then reduced to light yellow with 7% stannous chloride. Then, 50 mL of water was slowly added, and 5 mL of saturated mercuric chloride solution was added after cooling. After standing for 2-3 min, 20 mL of sulfuric acid was added, followed by 5-6 drops of 1% sodium diphenylamine sulfonate. Immediately, 1% potassium dichromate standard solution was added dropwise until the solution turned stable blue purple, which was the end point. The total iron content was calculated according to Formula 3. The total iron content (%) in the slag prepared in Examples 3-6 and Comparative Examples 1-6 was determined according to this method. The results are shown in Table 1.

[0103] Formula 3: Total iron content (%) = V x T x 100%

[0104] In Formula 3, V is the number of milliliters of 1% potassium dichromate standard solution consumed by 2 g of slag; and T is the total iron content of 2 g of standard sample per 2 g of standard sample consumed by 1% potassium dichromate standard solution.

[0105] Table 1 Effective sulfur content of slag, burnout rate, total iron content of slag statistics

[0106] Item Effective sulfur content of slag, % Burnout rate, % Total iron content of slag, % Example 3 0.29 99.31 62.0 Example 4 0.27 99.36 61.9 Example 5 0.27 99.36 62.2 Example 6 0.25 99.40 62.2 Comparative Example 1 0.63 98.50 59.2 Comparative Example 2 0.39 99.07 61.1 Comparative Example 3 0.36 99.14 61.4 Comparative Example 4 0.40 99.05 60.9 Comparative Example 5 0.60 98.57 59.7 Comparative Example 6 0.48 98.86 60.3

[0107] Data analysis:

[0108] As can be seen from Table 1, the processing technology has higher burnout rate and total iron content of slag;

[0109] This may be due to the fact that the present application is improved by the fluidized bed furnace, not only improves the residence time of pyrite combustion in the furnace, but also prolongs the residence time of furnace gas; the roasting of the modified fluidized bed furnace in the specific process makes the pyrite powder fully burn, which not only improves the burnout rate of pyrite and the iron grade of the roasted slag, reduces the total sulfur content of the roasted slag, but also reduces the generation of original acid mist and gaseous sulfur in the furnace gas, reduces the generation of sublimed sulfur in the purification section dynamic wave filler tower, thereby prolonging the resistance rising period, promoting the system resistance to be stable, prolonging the service life of the circulating pump of the dynamic wave and the filler tower, preventing the pump from running, dripping and leaking, and improving the acid production of the device. The present application carries out particle size screening treatment on pyrite powder before flotation and compounding according to a specific proportion, which improves the flotation efficiency, controls the volume expansion in the roasting process, and further controls the volume of the slag within the range that the slag roller can withstand. The special high-efficiency inhibitor obtained by mixing sodium hydrosulfite, sodium mercaptoacetate, sodium humate and sodium carbonate in the flotation process of the present application selectively maximizes the inhibition of group adsorption mass transfer on the mineral surface, weakens the oxidation mass transfer on the mineral surface, so that the mineral surface still has active area and site for the adsorption of collector, thereby making the floated pyrite more accurate. The present application improves the feed quality of the fluidized bed furnace, thereby further improving the acid production and the total iron content in the slag. Therefore, compared with the prior art, the pyrite processing technology of the present application not only has high burnout rate, but also has high iron grade of the slag.

[0110] It should be understood by those skilled in the art that the above discussion of any embodiment is only exemplary and is not intended to imply that the scope of the present application is limited to these examples; under the idea of the present application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in details.

[0111] The present application is intended to cover all such alternatives, modifications and variations as fall within the broad scope of the appended claims. Accordingly, any and all such modifications, variations, alternatives and equivalents should be considered to fall within the scope of the present application.

Claims

1. A process for the complete combustion of sulphur ores in a fluidized bed furnace, characterized in that, The method comprises the following steps: Step S1: crushing and screening pyrite, and then compounding to obtain compounded pyrite powder; Step S2: floating the compounded pyrite powder with a high-efficiency inhibitor to obtain pretreated pyrite powder; Step S3: adding the pretreated pyrite powder into a fluidized bed furnace, and then flattening and fully burning to obtain furnace gas and furnace slag; The high-efficiency inhibitor in step S2 is obtained by mixing sodium hydrosulfite, sodium mercaptoacetate, sodium humate and a buffer; In step S3, the furnace temperature during the full combustion treatment is 910-930 DEG C, the combustion time during the full combustion treatment is 4-5 h, the oxygen concentration at the outlet of the fluidized bed furnace during the full combustion treatment is 2.5%-3.0%, the negative pressure at the outlet of the fluidized bed furnace during the full combustion treatment is -0.6 kPa--0.4 kPa, and the furnace bottom pressure of the fluidized bed furnace during the full combustion treatment is 16.0 kPa-17.0 kPa; In step S1, the screening process is as follows: Firstly, screening with a screen having a pore size of 150 μm, then screening with a screen having a pore size of 48 μm, and then screening with a screen having a pore size of 38 μm, to obtain pyrite powder with a particle size of 48-150 μm, pyrite powder with a particle size of 38-48 μm and pyrite powder with a particle size of 0-38 μm; The compounded pyrite powder is obtained by mixing pyrite powder with a particle size of 48-150 μm, pyrite powder with a particle size of 38-48 μm and pyrite powder with a particle size of 0-38 μm in a mass ratio of 1-2:14-18:

80.

2. The process for the full combustion of sulphur ores in a fluidized bed furnace according to claim 1, characterized in that, The mass ratio of sodium hydrosulfite, sodium mercaptoacetate, sodium humate and the buffer is 2-3:1:1:1-2.

3. The process for the complete combustion of sulphur ores in a fluidized bed furnace as claimed in claim 1, wherein, In step S2, the floating process is as follows: Step A1: adding the compounded pyrite powder into water, stirring uniformly, then adding the high-efficiency inhibitor and maintaining the pH value of the slurry at 9-10, and then sequentially adding a collector and a foaming agent for 3-6 min of floating to obtain foam product 1 and tailings 1; Step A2: adding the high-efficiency inhibitor into tailings 1 and maintaining the pH value of the slurry at 9-10, and then sequentially adding the collector and the foaming agent for 1-3 min of scavenging to obtain foam product 2 and tailings 2; Step A3: mixing foam product 1 and foam product 2, then adding the high-efficiency inhibitor, and then cleaning for 1-3 min to obtain foam product 3 and tailings 3; Step A4: mixing tailings 2 and tailings 3, and then drying to obtain the pretreated pyrite powder.

4. The process for the full combustion of sulphur ores in a fluidized bed furnace according to claim 3, characterized in that, The buffer is any one or more of sodium phosphate, sodium carbonate and sodium borate; The collector is any one or more of sodium ethyl xanthate, sodium butyl xanthate and sodium dibutyl dithiophosphate; The foaming agent is any one or more of pine oil, methyl isobutyl carbinol and camphor oil.

5. The process for the complete combustion of sulphur ores in a fluidized bed furnace as claimed in claim 3, wherein, In step A1, the mass ratio of the water to the compounded pyrite powder is 100:15-25; In step A1, the amount of the high-efficiency inhibitor is 900-1100 g / t; In step A1, the amount of the collector is 100-200 g / t; In step A1, the amount of the foaming agent is 30-60 g / t.

6. The process for the complete combustion of sulphur ores in a fluidized bed furnace as claimed in claim 3, wherein, In step A2, the amount of the high-efficiency inhibitor is 300-600 g / t; The dosage of the collector in step A2 is 20-60 g / t; The dosage of the frother in step A2 is 6-20 g / t.

7. The process for the full combustion of sulphur ores in a fluidized bed furnace according to claim 3, characterized in that, The dosage of the high-efficiency inhibitor in step A3 is 300-900 g / t.

8. The process for the full combustion of sulphur ores in a fluidized bed furnace according to claim 1, characterized in that, The thickness of the pre-treated pyrite powder in the roaster after spreading in step S3 is 550-600 mm.