A method for removing sulfur from high-sulfur magnetite

Abstract

The invention discloses a method for removing sulfur from high-sulfur magnetite. The method comprises the following steps: activating pyrrhotite by a combined activator in an alkaline environment, flotation separation of pyrrhotite and pyrite, and achieving the purpose of removing sulfur. The combined activator comprises sodium sulfide, sodium fluorosilicate, and sodium gluconate, the combined collector comprises isoamyl xanthate and butylammonium black medicine, and the foaming agent is 2# oil. The activator sodium sulfide is added to a mill feed port, the ore is ground, the slurry concentration is adjusted, and the ore is fed into a flotation tank. The combined activator is added and stirred for activation. The combined collector and the foaming agent are added and stirred for aeration, and the sulfur concentrate is collected. The slurry after flotation is subjected to magnetic separation to separate iron concentrate and non-magnetic gangue, thereby achieving the purpose of removing sulfur from the iron concentrate. The method adopts a method of using a combined activator + a composite collector in an alkaline environment, can achieve an effect of 1+1 being greater than 2, solves the problem of difficulty in removing pyrrhotite from magnetite in the prior art, and achieves the purpose of efficiently removing sulfur from high-sulfur magnetite in an alkaline environment.

Description

Technical Field

[0001] The invention discloses a method for removing sulfur from high-sulfur magnetite and relates to the field of mineral processing. Background Art

[0002] Iron ore is the primary raw material for the steel industry and a key national strategic resource. However, most Chinese iron ore is characterized by being "poor, fine, and impure," requiring beneficiation. Therefore, research and production efforts must focus on improving the grade of iron concentrate and reducing the levels of harmful impurities such as S, P, Al2O3, and SiO2. The large-scale import of high-grade, high-quality foreign iron ore has offset my country's limited iron ore resources and lower quality, improving the iron grade and quality of blast furnace feedstock. Foreign iron ore, with high iron content and low silicon, aluminum, phosphorus, and sulfur, offers a landed price comparable to domestically produced iron concentrate, making it highly competitive in the Chinese market. Consequently, domestic iron mines must prioritize improving the grade of their iron concentrates and reducing impurities.

[0003] The sulfur content in iron ore will directly affect the quality of the steel produced, so iron ore desulfurization becomes a very important part of the iron ore beneficiation process.

[0004] The grinding-magnetic-flotation combined process is usually used to extract iron and reduce sulfur in high-sulfur magnetite ore. That is, the ore is first ground to a suitable grinding particle size, and then the tailings are discarded by weak magnetic separation to obtain magnetite concentrate with qualified iron grade, and then the magnetite concentrate is subjected to reverse flotation desulfurization.

[0005] The chemical composition of pyrite is FeS2. Since pyrite is rich in sulfur, it is usually used as the main mineral raw material for extracting sulfur and making sulfuric acid in sulfuric acid plants. 2- Ions form anion clusters [S2] 2- When pyrite is crushed, it presents complete crystals. Its cleavage surface is oleophilic and hydrophobic. Xanthate collectors can easily form hydrophobic dixanthate on its surface, which is beneficial to the flotation of pyrite. Therefore, the flotation separation of pyrite and magnet is relatively easy.

[0006] Pyrrhotite Fe 1-X S (X = 0.1-0.2) is an iron sulfide mineral in the pyrrhotite family. It contains up to 40% sulfur and can be used as a raw material for sulfuric acid production. Pyrrhotite has a metallic luster and a dark bronze-yellow color with a reddish hue. It typically occurs in massive masses within copper-nickel sulfide deposits. Its crystal forms range from hexagonal plates, columns, or barrels, but these are rare, typically occurring as dense, massive aggregates.

[0007] Pyrrhotite exhibits polymorphic variations in the monoclinic, hexagonal, and orthorhombic crystal systems. Orthorhombic pyrrhotite is rare, and most pyrrhotite is a mixture of monoclinic and hexagonal crystals. Pyrrhotite's physical properties, chemical composition, and crystal structure directly determine its flotation characteristics, surface oxidation susceptibility, and brittleness. Its floatability is poor, making it a difficult-to-float iron sulfide mineral.

[0008] The main reason why the desulfurization problem of magnetite has become a hindrance to the quality of iron ore concentrate products is that pyrrhotite is difficult to separate from magnetite. The reasons can be summarized into four aspects: (1) Magnetite and pyrrhotite have similar densities and magnetic properties. Even by reducing the magnetic induction intensity, pyrrhotite cannot be effectively separated. In addition, magnetite and pyrrhotite are not only easy to produce magnetic agglomeration themselves, but also easy to produce heterogeneous magnetic agglomeration through the effect of residual magnetism after magnetic separation. Fine-grained pyrrhotite will adhere to the surface of magnetite due to magnetization. When the mineral particle size is fine, the magnetic agglomeration phenomenon will be more serious, making it difficult to effectively separate the two. This has been confirmed in many industrial practices; (2) The floatability of hexagonal pyrrhotite is worse than that of single crystal pyrrhotite. The floatability of the two is different. It is difficult to remove the pyrrhotite of the two crystal systems from magnetite under the same separation conditions; (3) The surface oxidation rate of pyrrhotite is very fast. According to reports, under the same conditions, the oxidation rate of pyrrhotite will reach 20 or even 100 times that of pyrite. Under certain conditions, Although elemental sulfur is generated when the surface of the lower pyrrhotite is oxidized to form Fe2(SO4)3 and FeSO4, its surface area increases after mudification, which makes it easy to be severely oxidized, and further forms a hydrophilic layer of iron hydroxide on the surface, resulting in a decrease in its floatability; (4) Experimental studies have shown that if bubbles want to adhere to mineral particles, the energy barrier between the bubbles and the mineral particles must be overcome first, and only in this case can effective adhesion occur when the contact angle is greater than 0 degrees. The existence of energy barrier is the primary obstacle that makes the adhesion process difficult. The fine-grained pyrrhotite after mudification has a low mass and momentum, and the probability of collision with bubbles is low. It is difficult to overcome the energy barrier between the fine-grained pyrrhotite and the bubbles and adhere to the bubble surface, making it difficult for the pyrrhotite to float.

[0009] To address the difficulty of flotation separation of magnetite and pyrrhotite, relevant technicians have conducted extensive research and concluded that activators for pyrrhotite include copper sulfate, sodium sulfide, sodium fluorosilicate, oxalic acid, sulfuric acid, MHH-1, NH, copper sulfate + sulfuric acid, oxalic acid + copper sulfate, sodium thiosulfate + water glass + sulfuric acid, and copper sulfate + water glass. These activators are effective for flotation separation of some magnetite and pyrrhotite, but due to the significant differences in the properties of different sulfur-containing minerals, these activators cannot achieve satisfactory flotation separation results for all magnetite and pyrrhotite. For example, at a high-sulfur magnetite mine in Daye City, Hubei Province, the above activators were ineffective in flotation separation of magnetite and pyrrhotite. The raw ore contained 56% TFe and 9.8% TS, and 90% of the sulfur-containing minerals was pyrrhotite. However, after activation with these activators, the iron ore concentrate recovered by magnetic separation still contained as much as 9% sulfur. This extremely high sulfur content made the iron ore concentrate daunting for steel manufacturers, resulting in unsalable and unregulated goods. Despite research efforts by multiple research institutions and departments, the high sulfur content in iron ore concentrate could not be reduced, causing serious economic losses to the mine.

[0010] Furthermore, most existing methods for desulfurizing magnetite containing pyrrhotite involve activated flotation desulfurization of the pyrrhotite under acidic conditions. For example, Chinese invention patent CN 108097452A discloses a "process for producing high-quality iron concentrate from iron ore." Aluminum sulfate, a mixture of aluminum sulfate and ammonium fluosilicate in a mass ratio of 3-1:1-2, or a mixture of aluminum sulfate and sodium phosphate in a mass ratio of 1-2:3-2, is used as a pH adjuster and activator for the pyrrhotite. Flotation desulfurization is performed under conditions adjusted to a pH of 4.5-5.5. However, acidic conditions severely corrode flotation equipment and pipelines, resulting in high reagent consumption and high industrial production costs.

[0011] Therefore, a new desulfurization technology with excellent research and development effect, strong adaptability and the ability to activate pyrrhotite in an alkaline environment is a scientific research project that needs to be tackled urgently. It is more practical than the desulfurization technology of activating pyrrhotite in an alkaline environment rather than in an acidic environment. Summary of the Invention

[0012] To address the problems identified in the aforementioned background technology, the present invention discloses a method for removing sulfur from high-sulfur magnetite. The method utilizes a combination of activators to activate pyrrhotite in an alkaline environment, followed by flotation separation of the pyrrhotite to achieve the purpose of removing sulfur. The combination activator comprises sodium sulfide, sodium fluorosilicate, and sodium gluconate; the combination collector comprises isopentyl xanthate and butylammonium xanthate; and the foaming agent is 2# oil. This method can effectively activate pyrrhotite and reduce the sulfur content in iron concentrate to below 0.3%.

[0013] In the above-mentioned method for removing sulfur from high-sulfur magnetite, the dosage ratio of the combined activator is sodium sulfide: sodium fluorosilicate: sodium gluconate = 2-4: 3-12: 1-2 by mass.

[0014] A further method for removing sulfur from high-sulfur magnetite is provided, wherein the mass ratio of the combined activating agent is sodium sulfide: sodium fluorosilicate: sodium gluconate = 3:9:1.5.

[0015] In the above-mentioned method for removing sulfur from high-sulfur magnetite, the mass ratio of the combined collector is 3:1, that of isopentyl xanthate and butylammonium black medicine.

[0016] In the above-mentioned method for removing sulfur from high-sulfur magnetite, the foaming agent is 2# oil.

[0017] The present invention provides a method for removing sulfur from high-sulfur magnetite. The dosage of a combined activator, a combined collector and a foaming agent increases or decreases according to the pyrrhotite content in the magnetite. The dosage of the combined activator, the combined collector and the foaming agent is proportional to the pyrrhotite content in the magnetite.

[0018] The present invention discloses a method for removing sulfur from high-sulfur magnetite. The sodium sulfide as one of the combined activators is added in full at the feed port of a ball mill. The other combined activators, a collector and a foaming agent No. 2 oil are added in a proportion of 40% to 60% of the total amount of the added agents in the roughing process, and in a proportion of 40% to 60% of the total amount of the added agents in the first to fourth sweep processes.

[0019] A method for removing sulfur from high-sulfur magnetite, specifically comprising the following steps:

[0020] 1) The raw ore is crushed and ground into a ball mill. 100-1000 g / t of sodium sulfide is added based on the dry weight of the ore. The solid-liquid ratio of the grinding is 1:1 and the grinding fineness reaches -200 mesh, accounting for 50%-90%;

[0021] 2) Adjust the slurry concentration to 35%-50% before entering the flotation tank. Calculate the dosage based on the dry weight of the mineral. Add the combined activator sodium fluorosilicate 1000-3000 g / ton and sodium gluconate 100-400 g / ton in sequence. Stir and activate for 3-7 minutes.

[0022] 3) Add 90-500 g / ton of isoamyl xanthate and 30-170 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 3-5 minutes;

[0023] 4) Add 10-120 g / ton of 2# foaming agent oil based on the dry weight of the mineral, stir and activate for 2-3 minutes, aerate and scoop out the sulfur concentrate;

[0024] 5) Flotation adopts a process of roughing first, scavenging second to fourth to separate sulfur ore, and cleaning third to fourth to purify sulfur concentrate;

[0025] 6) The slurry after flotation enters the drum magnetic separator for magnetic separation to separate the magnetite from the non-magnetic gangue and obtain qualified magnetite concentrate.

[0026] The present invention provides a method for removing sulfur from high-sulfur magnetite, which is combined with sodium sulfide as one of the activators. Sodium sulfide is commonly used in the sulfide flotation of oxide ores, that is, as a sulfiding agent for oxide ores, it can form a sulfide ore film on the surface of the oxide ore, effectively alleviate the mudification and oxidation of pyrrhotite during the grinding process, and also serve as a pH alkaline regulator.

[0027] Sodium fluorosilicate, one of the combined activators, can produce hydrofluoric acid upon hydrolysis, which can effectively clean the surface of sulfide mineral particles and also has a strong sludge dispersing effect.

[0028] Sodium gluconate, one of the combined activators, is an organic compound with a wide range of industrial applications. It serves as a highly effective chelating agent in the construction, textile printing and dyeing, metal surface treatment, and water treatment industries. It is also a steel surface cleaner, a glass bottle cleaner, and an alumina colorant in the electroplating industry. In the concrete industry, it is used as a highly effective retarder and water reducer. Sodium gluconate has high scale inhibition properties and is a green scale inhibitor. It can also effectively remove calcium, magnesium, and iron ions from the slurry, forming a precipitate. This prevents pyrrhotite surface contamination under alkaline conditions, facilitates collector capture, and reduces collector molecule consumption.

[0029] The present invention discloses a method for removing sulfur from high-sulfur magnetite, which adopts a process flow of flotation followed by magnetization in an alkaline environment and a treatment method combining an activator and a composite collector, achieving a "1+1 greater than 2" effect. Through experiments and industrial production verification, the sulfur content of the iron concentrate was reduced to below 0.3%, the iron concentrate to approximately 68%, and the iron recovery rate reached over 88%. This method effectively solves the problem of difficult separation of magnetite and pyrrhotite in the prior art, achieves the goal of efficiently removing sulfur from high-sulfur magnetite in an alkaline environment, and achieves highly satisfactory results. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the process flow chart of combined activation flotation. DETAILED DESCRIPTION

[0031] Example 1

[0032] A high-sulfur magnetite mine in Daye City, Hubei Province has a raw ore content of TFe 54.37%, TS 9.8%, and 80% of the sulfur minerals are pyrrhotite.

[0033] 1) The raw ore is crushed and ground into a ball mill. 1000 g / t of sodium sulfide is added based on the dry weight of the ore. The solid-liquid ratio of the grinding is 1:1, and the grinding fineness reaches -200 mesh, accounting for 80%;

[0034] 2) Adjust the slurry concentration to 40% before entering the flotation tank. Calculate the dosage based on the dry weight of the minerals. Add the combined activator sodium fluorosilicate 1500 g / ton and sodium gluconate 150 g / ton in sequence. Stir and activate for 6 minutes.

[0035] 3) Add 100 g / ton of isoamyl xanthate and 35 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 5 minutes;

[0036] 4) Add 50 g / ton of 2# foaming agent based on the dry weight of the mineral, stir for 2 minutes, aerate and scrape the sulfur ore for 5 minutes;

[0037] 5) After the roughing is completed, add the combined activator sodium fluorosilicate 750 g / ton and sodium gluconate 75 g / ton in sequence and stir to activate for 4 minutes;

[0038] 6) Add 50 g / ton of isoamyl xanthate and 17 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 4 minutes;

[0039] 7) Add 20 g / ton of foaming agent 2# oil based on the dry weight of the mineral, stir for 2 minutes, and aerate and sweep the sulfur ore for 5 minutes;

[0040] 8) After the scavenging is completed, add the combined activator sodium fluorosilicate 750 g / ton and sodium gluconate 75 g / ton in sequence and stir to activate for 4 minutes;

[0041] 9) Add 50 g / ton of isoamyl xanthate and 17 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 4 minutes;

[0042] 10) Add 10 g / t of 2# oil as a foaming agent based on the dry weight of the mineral, stir for 2 minutes, and aerate and sweep the sulfur concentrate for 3 minutes;

[0043] 11) After the second scavenging, add 30 g / t of isoamyl xanthate and 10 g / t of butyl ammonium xanthate in order based on the dry weight of the minerals, and stir to activate for 3 minutes;

[0044] 12) Add 10 g / t of 2# oil as a foaming agent based on the dry weight of the mineral, stir for 2 minutes, and aerate and sweep the sulfur ore for 3 minutes;

[0045] 13) After flotation, the pulp enters the drum magnetic separator for magnetic separation, where the magnetite is separated from the non-magnetic gangue to obtain qualified magnetite concentrate powder.

[0046] The iron ore concentrate powder was tested to contain 68.98% iron and 0.29% sulfur, achieving excellent results and solving a major problem for the mining company while also bringing significant economic benefits to the company.

[0047] Example 2

[0048] In a high-sulfur magnetite mine in Ezhou City, Hubei Province, the original ore contains TFe 58.7%, TS 4.3%, and 70% of the sulfur minerals are pyrrhotite.

[0049] 1) The raw ore is crushed and ground into a ball mill. 900 g / t of sodium sulfide is added based on the dry weight of the ore. The solid-liquid ratio of the grinding is 1:1, and the grinding fineness reaches -200 mesh, accounting for 75%;

[0050] 2) Adjust the slurry concentration to 40% before entering the flotation tank. Calculate the dosage based on the dry weight of the minerals. Add the combined activator sodium fluorosilicate 1000 g / ton and sodium gluconate 100 g / ton in sequence. Stir and activate for 6 minutes.

[0051] 3) Add 90 g / ton of isoamyl xanthate and 30 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 5 minutes;

[0052] 4) Add 40 g / ton of 2# oil as a foaming agent based on the dry weight of the mineral, stir for 2 minutes, aerate and scrape the sulfur ore for 5 minutes;

[0053] 5) After the roughing is completed, add the combined activator sodium fluorosilicate 500 g / ton and sodium gluconate 50 g / ton in sequence and stir to activate for 4 minutes;

[0054] 6) Add 50 g / ton of isoamyl xanthate and 17 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 4 minutes;

[0055] 7) Add 20 g / ton of foaming agent 2# oil based on the dry weight of the mineral, stir for 2 minutes, and aerate and sweep the sulfur ore for 5 minutes;

[0056] 8) After the first scavenging is completed, add 500 g / ton of sodium fluorosilicate and 50 g / ton of sodium gluconate as combined activators and stir to activate for 4 minutes;

[0057] 9) Add 50 g / ton of isoamyl xanthate and 17 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 4 minutes;

[0058] 10) Add 10 g / t of 2# oil as a foaming agent based on the dry weight of the mineral, stir for 2 minutes, and aerate and sweep the sulfur concentrate for 3 minutes;

[0059] 11) After the second scavenging, add 30 g / t of isoamyl xanthate and 10 g / t of butyl ammonium xanthate in order based on the dry weight of the minerals, and stir to activate for 3 minutes;

[0060] 12) Add 10 g / t of 2# oil as a foaming agent based on the dry weight of the mineral, stir for 2 minutes, and aerate and sweep the sulfur ore for 3 minutes;

[0061] 13) After flotation, the pulp enters the drum magnetic separator for magnetic separation, where the magnetite is separated from the non-magnetic gangue to obtain qualified magnetite concentrate powder.

[0062] The iron ore concentrate powder was tested to contain 68.87% iron and 0.21% sulfur, achieving excellent results, solving a difficult problem for the mining company and bringing great economic benefits to the company.

[0063] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for removing sulfur from high-sulfur magnetite, characterized in that: The method uses a combined activator to activate pyrrhotite in an alkaline environment, and flotation separation of the pyrrhotite to achieve the purpose of removing sulfur. The combined activator is composed of sodium sulfide, sodium fluorosilicate, and sodium gluconate, and the mass ratio of the combined activator is sodium sulfide: sodium fluorosilicate: sodium gluconate = 3:9:1.

5. The combined collector is composed of isopentyl xanthate and butylammonium black powder, and the mass ratio of the combined collector is isopentyl xanthate: butylammonium black powder is 3:

1. The foaming agent is 2# oil. The method can effectively activate pyrrhotite under alkaline conditions and effectively reduce the sulfur content in the iron ore concentrate to below 0.3%. The specific implementation includes the following steps: 1) The raw ore is crushed and then ground in a ball mill with a solid-liquid ratio of 1:

1. 100-1000 g / t of sodium sulfide is added based on the dry weight of the ore. The grinding fineness reaches -200 mesh, accounting for 50%-90%; 2) Adjust the slurry concentration to 35%-50% before entering the flotation tank. Calculate the dosage based on the dry weight of the mineral. Add the combined activator sodium fluorosilicate 1000-3000 g / ton and sodium gluconate 100-400 g / ton in sequence. Stir and activate for 3-7 minutes. 3) Add 90-500 g / ton of isoamyl xanthate and 30-170 g / ton of butyl ammonium xanthate collectors in order based on the dry weight of the mineral, and stir to activate for 3-5 minutes; 4) Add 10-120 g / ton of 2# foaming agent oil based on the dry weight of the mineral, stir and activate for 2-3 minutes, aerate and scoop out the sulfur concentrate; 5) Flotation adopts a process of roughing first, scavenging second to fourth to separate sulfur ore, and cleaning third to fourth to purify sulfur concentrate; 6) The slurry after flotation enters the drum magnetic separator for magnetic separation to separate the magnetite from the non-magnetic gangue to obtain qualified magnetite concentrate; Sodium sulfide, one of the combined activators, is added in full at the feed port of the ball mill.

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