阅读说明：本技术 一种高硫磁铁矿精矿的氧化脱硫方法 (Oxidation desulfurization method of high-sulfur magnetite concentrate ) 是由 吴文红 王秋林 刘双安 张立刚 梅灿国 吴承优 杨晓峰 于 2019-11-13 设计创作，主要内容包括：本发明涉及一种高硫磁铁矿精矿的氧化脱硫方法,亦即预氧化—弱磁选脱硫工艺,其特征在于：将强氧化剂与含硫量＞0.3％的高硫磁铁矿精矿给矿混合给入磨机与旋流器组成的闭路磨矿作业中,强氧化剂与磁黄铁矿进行氧化还原反应,将磁黄铁矿氧化成Fe<Sub>2</Sub>(SO<Sub>4</Sub>)<Sub>3</Sub>弱磁性矿物甚至非磁性矿物,增大目的矿物与含硫杂质矿物比磁化系数的差异,然后采用弱磁选工艺脱除磁黄铁矿,获得含硫量＜0.2％的磁铁矿精矿；若高硫磁铁矿精矿给矿粒度足够细,可以不采用闭路磨矿作业,加入搅拌槽中氧化反应即可。与现有技术相比,本发明的优点是：氧化脱硫方法用于脱除高硫磁铁矿精矿中的磁黄铁矿,具有流程简单、操作便捷、效率高、成本低、绿色环保等特点。(The invention relates to an oxidation desulfurization method of high-sulfur magnetite concentrate, namely a preoxidation-low-intensity magnetic separation desulfurization process, which is characterized in that: in the closed circuit grinding operation formed by feeding and mixing a strong oxidant and high-sulfur magnetite concentrate with the sulfur content of more than 0.3 percent into a grinding machine and a swirler, the strong oxidant and pyrrhotite are subjected to oxidation-reduction reaction to oxidize the pyrrhotite into Fe 2 (SO 4 ) 3 Weakly magnetic minerals and even non-magnetic minerals increase the difference of specific magnetization coefficients of target minerals and sulfur-containing impurity minerals, and then a weak magnetic separation process is adopted to remove pyrrhotite to obtain magnetite concentrate with the sulfur content of less than 0.2%; if the ore feeding granularity of the high-sulfur magnetite concentrate is fine enough, closed circuit grinding operation can be omitted,adding the mixture into a stirring tank for oxidation reaction. Compared with the prior art, the invention has the advantages that: the oxidative desulfurization method is used for removing pyrrhotite in the high-sulfur magnetite concentrate, and has the characteristics of simple process, convenience and quickness in operation, high efficiency, low cost, environmental friendliness and the like.)

1. An oxidation desulfurization method of high-sulfur magnetite concentrate, namely a pre-oxidation-low-intensity magnetic separation desulfurization process, is characterized in that: in the closed circuit grinding operation formed by feeding and mixing a strong oxidant and high-sulfur magnetite concentrate with the sulfur content of more than 0.3 percent into a grinding machine and a swirler, the strong oxidant and pyrrhotite are subjected to oxidation-reduction reaction to oxidize the pyrrhotite into weak magnetic iron mineral Fe₂(SO₄)₃Then removing pyrrhotite by adopting a low-intensity magnetic separation process to obtain magnetite concentrate with the sulfur content of less than 0.2 percent, and specifically comprising the following steps of:

s1, weighing strong oxidant

Weighing strong oxidant according to the proportion of 5-10% of the weight of the high-sulfur magnetite concentrate;

s2, feeding and mixing the strong oxidant and the high-sulfur magnetite concentrate:

mixing the strong oxidant weighed in the step S1 into the high-sulfur magnetite concentrate feed ore;

s3, carrying out oxidation-reduction reaction

Feeding the mixture obtained in the step S2 into a closed circuit grinding operation consisting of a grinder and a swirler, and carrying out oxidation-reduction reaction on hydrogen peroxide and pyrrhotite for 10-60 min to obtain a graded overflow product of the closed circuit grinding operation with the fineness of-0.075 mm accounting for more than 95%;

s4, removing pyrrhotite by adopting a low-intensity magnetic separation process

Feeding the classification overflow product of the closed circuit grinding operation into a primary-secondary-fine two-stage continuous low-intensity magnetic separation process for separation to obtain a low-intensity magnetic separation concentrate product, a low-intensity magnetic separation roughing tailing product and a low-intensity magnetic separation concentration tailing product; the low-intensity magnetic separation concentrate product is magnetite concentrate, and the sulfur content of the magnetite concentrate is less than 0.2 percent; combining the low-intensity magnetic separation rough concentration tailing product and the low-intensity magnetic separation fine concentration tailing product into a low-intensity magnetic separation tailing product, and oxidizing the low-intensity magnetic separation tailing product into Fe₂(SO₄)₃The pyrrhotite of the weakly magnetic minerals becomes a tailing product of the weak magnetic separation.

2. The oxidative desulfurization method of high-sulfur magnetite concentrate according to claim 1, characterized in that the strong oxidant is hydrogen peroxide, potassium permanganate, potassium perchlorate, or bleaching powder.

3. The oxidative desulfurization method for the high-sulfur magnetite concentrate according to claim 1, characterized in that the low-intensity magnetic separation process is performed by using a low-intensity magnetic separator with a magnetic field strength of 800-3000 Gs under the condition of an ore feeding concentration of 20-40%.

Technical Field

The invention belongs to the technical field of mineral processing, and particularly relates to an oxidative desulfurization method for high-sulfur magnetite concentrate.

Background

The iron ore resources in China are characterized by 'poor, fine and miscellaneous', and the 'miscellaneous' is the symbiosis of various useful minerals. The sulfur-containing magnetite ore generally refers to magnetite ore of which the useful mineral is mainly magnetite and contains sulfur-containing iron minerals such as pyrrhotite and the like, wherein the pyrrhotite is characterized by strong magnetism, easy argillization, oxidation and poor floatability, and the sulfur mainly refers to sulfur in the pyrrhotite. The content of sulfur is an important standard for measuring the quality of iron ore concentrate, and the content of sulfur impurities in the iron ore concentrate fed into a furnace generally requires that TS is less than 0.30 percent. The high sulfur content in iron ore concentrate directly affects the quality of steel, and harms the production of blast furnace, and the sulfur discharge also causes environmental pollution.

The ore dressing process for treating the sulfur-containing magnetite ore is characterized in that the ore with lower sulfur content is treated, desulfurization is not considered, the production is usually carried out by adopting the conventional stage ore grinding-stage low-intensity magnetic separation process flow, pyrrhotite cannot be effectively removed by adopting a single low-intensity magnetic separation process, and the pyrrhotite is obviously enriched in the iron ore concentrate, so that the sulfur content of the iron ore concentrate exceeds the standard and the quality is unqualified due to the change of the sulfur content of the raw ore; and the other method is to treat the iron ore with higher sulfur content, and in consideration of desulfurization, a combined process flow of stage grinding, stage low-intensity magnetic separation and flotation is usually adopted, namely, the low-intensity magnetic separation is firstly used for obtaining the magnetite concentrate with qualified iron grade, and then the reverse flotation desulfurization is carried out on the magnetite concentrate to obtain the final magnetite concentrate with qualified sulfur content. However, the combined process flow needs to add concentrated sulfuric acid for size mixing and cleaning the surface of pyrrhotite during reverse flotation and desulfurization, so that the pyrrhotite can float upwards and be separated from the magnetite concentrate after the sulfide collecting agent is added, and the aim of desulfurization of the magnetite concentrate is fulfilled. The defects of the combined process flow are as follows: firstly, the operation control difficulty of concentrated sulfuric acid in production is high, and production accidents are easily caused; secondly, the process flow is long, and the mineral separation cost is increased; and thirdly, the flotation process is used for carrying out magnetite concentrate desulfurization, so that the pressure of subsequent wastewater treatment and environmental management is increased.

The desulfurization of high-sulfur iron ore concentrate is a major problem in the current iron ore dressing, the separation of magnetite concentrate and pyrrhotite is realized, and the removal of pyrrhotite in the iron ore concentrate is an industrial problem. Therefore, the purpose of removing pyrrhotite in the iron ore concentrate by researching and developing an environment-friendly non-flotation process to realize the desulfurization of the iron ore concentrate is to play an important role in promoting the development of the steel industry and environmental protection in China, and is imperative.

Disclosure of Invention

Aiming at the defects of the method for removing pyrrhotite from the high-sulfur magnetite concentrate by reverse flotation, the invention aims to provide the oxidative desulfurization method for the high-sulfur magnetite concentrate, establish the environment-friendly pre-oxidation-low intensity magnetic separation process for desulfurization of the high-sulfur magnetite concentrate, and realize the purpose that the content TS of sulfur impurities in the high-sulfur magnetite concentrate is less than 0.30 percent.

The purpose of the invention is realized by the following technical scheme:

the invention relates to an oxidation desulfurization method of high-sulfur magnetite concentrate, namely a preoxidation-low-intensity magnetic separation desulfurization process, which is characterized in that: mixing a strong oxidant and the high-sulfur magnetite concentrate, feeding the mixture into a closed circuit grinding operation consisting of a grinding machine and a swirler, carrying out oxidation-reduction reaction on the strong oxidant and pyrrhotite, and oxidizing the pyrrhotite into Fe₂(SO₄)₃Weakly magnetic minerals, and then removing pyrrhotite by adopting a weak magnetic separation process to obtain magnetite concentrate with qualified sulfur content (generally S is less than 0.2 percent), which specifically comprises the following steps:

s1, weighing strong oxidant

Weighing a strong oxidant according to the proportion of 5-10% of the weight of the high-sulfur magnetite concentrate;

s2, feeding and mixing the strong oxidant and the high-sulfur magnetite concentrate:

mixing the strong oxidant weighed in the step S1 into the high-sulfur magnetite concentrate feed ore;

s3, carrying out oxidation-reduction reaction

Feeding the mixture obtained in the step S2 into a closed circuit grinding operation consisting of a grinder and a swirler, and carrying out oxidation-reduction reaction on hydrogen peroxide and pyrrhotite for 10-60 min to obtain a graded overflow product of the closed circuit grinding operation with the fineness of-0.075 mm accounting for more than 95%;

s4, removing pyrrhotite by adopting a low-intensity magnetic separation process

Feeding the classification overflow product of the closed circuit grinding operation into a primary-secondary-fine two-stage continuous low-intensity magnetic separation process for separation to obtain a low-intensity magnetic separation concentrate product, a low-intensity magnetic separation roughing tailing product and a low-intensity magnetic separation concentration tailing product; the low-intensity magnetic separation concentrate product is magnetite concentrate, and the sulfur content of the magnetite concentrate is less than 0.2 percent; combining the low-intensity magnetic separation rough concentration tailing product and the low-intensity magnetic separation fine concentration tailing product into a low-intensity magnetic separation tailing product, and oxidizing the low-intensity magnetic separation tailing product into Fe₂(SO₄)₃The pyrrhotite of the weakly magnetic minerals becomes a tailing product of the weak magnetic separation.

The strong oxidant is hydrogen peroxide, potassium permanganate, potassium perchlorate or bleaching powder.

The low-intensity magnetic separation process is carried out by adopting a low-intensity magnetic separator with the appropriate magnetic field intensity of 800 Gs-3000 Gs under the condition that the ore feeding concentration is 20% -40%.

Principle of oxidation-reduction reaction of pyrrhotite

The molecular formula of pyrrhotite: fe_1-xS, its theoretical composition (wB%): fe 63.53%, S36.47%. Actually, the sulfur content can reach 39-40%, because part of Fe²⁺Quilt Fe³⁺Instead, to maintain electrovalence balance, in Fe²⁺A vacancy occurs at a location, referred to as an absent formation. Therefore, the general formula of pyrrhotite is often Fe_1-XAnd S represents. In the formula, x represents a defect number (structural vacancy) of an Fe atom, and x is 0.333.

The oxidation reaction equation of pyrrhotite and hydrogen peroxide is as follows:

3Fe_0.667S+12H₂O₂＝Fe₂(SO₄)₃+12H₂O

compared with the prior art, the invention has the advantages that:

the oxidative desulfurization method is used for removing pyrrhotite in the high-sulfur magnetite concentrate, namely, the pre-oxidation-low-intensity magnetic separation process is adopted for desulfurization, and the oxidative desulfurization method has the characteristics of simple flow, convenience in operation, high efficiency, low cost, environmental friendliness and the like.

Drawings

FIG. 1 is a flow chart of the principle of the pre-oxidation-low-intensity magnetic separation desulfurization process of the present invention.

Detailed Description

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

the chemical multi-element analysis and iron phase analysis results of the iron ore concentrate produced by a low-grade high-sulfur magnetite concentrating plant by adopting the process flows of coarse grain preselection, stage grinding and stage weak magnetic separation are respectively shown in tables 1 and 2.

Table 1 analysis result of main chemical composition of iron ore concentrate (%)

Table 2 chemical phase analysis result (%) of iron in iron ore concentrate

The results of the analyses in tables 1 and 2 show that: the sulfur content of the iron ore concentrate reaches 0.8%, and the standard that the content of sulfur impurities in the iron ore concentrate generally requires TS to be less than 0.30% is seriously exceeded, and sulfur reduction is needed.

Through comprehensive research of microscopic identification, X-ray diffraction analysis and scanning electron microscope analysis, the main mineral types of the iron ore concentrate are simpler, and the iron ore is single magnetite; the metal sulfide mineral is pyrrhotite; the gangue minerals are mainly quartz. The pyrrhotite is mostly embedded in the magnetite in an irregular granular, fine-vein, lenticular or serpentine shape in a star-dispersed dip dyeing shape, part of the pyrrhotite is filled along the edge of the magnetite or among the magnetite particles for substitution, the granularity is 0.01-0.15 mm, the shape is relatively regular, the semi-self-shaped sheet shape is more, the minority is irregular, the pyrrhotite is a strong magnetic mineral, and the pyrrhotite is easy to enter into the iron ore concentrate along with the magnetite in the weak magnetic separation process, so the content of sulfur in the iron ore concentrate is higher, and the pyrrhotite is high-sulfur magnetite concentrate.

As shown in figure 1, the oxidation desulfurization method of the high-sulfur magnetite concentrate is applied, namely, the high-sulfur magnetite concentrate is treated by a pre-oxidation-low-intensity magnetic separation desulfurization process, strong oxidant hydrogen peroxide and the high-sulfur magnetite concentrate with the sulfur content of 0.8 percent are fed into a closed circuit grinding operation consisting of a ball mill and a swirler in a mixed mode, the hydrogen peroxide and pyrrhotite are subjected to oxidation reduction reaction, and the pyrrhotite is oxidized into Fe₂(SO₄)₃Weakly magnetic minerals and even non-magnetic minerals increase the difference of specific magnetization coefficients of target minerals and sulfur-containing impurity minerals, and then the weak magnetic separation process is adopted to remove pyrrhotite to obtain magnetite concentrate with the sulfur content of 0.09%. The method specifically comprises the following steps:

s1, weighing strong oxidant hydrogen peroxide

Hydrogen peroxide is weighed according to the proportion of 10 percent of the weight of the high-sulfur magnetite concentrate;

s2, feeding and mixing hydrogen peroxide and the high-sulfur magnetite concentrate:

mixing the hydrogen peroxide weighed in the step S1 into the high-sulfur magnetite concentrate feed;

s3, carrying out oxidation-reduction reaction

Feeding the mixture obtained in the step S2 into a closed circuit grinding operation consisting of a ball mill and a swirler, and carrying out oxidation-reduction reaction on hydrogen peroxide and pyrrhotite for 30min to obtain a graded overflow product of the closed circuit grinding operation with the fineness of-0.075 mm accounting for 96%;

s4, removing pyrrhotite by adopting a low-intensity magnetic separation process

Feeding the classification overflow product of the closed circuit grinding operation into a primary-secondary-fine two-stage continuous low-intensity magnetic separation process for separation to obtain a low-intensity magnetic separation concentrate product, a low-intensity magnetic separation roughing tailing product and a low-intensity magnetic separation concentration tailing product; the concentrate product of the low intensity magnetic separation is magnetThe sulfur content of the iron ore concentrate and the magnetite concentrate is 0.09 percent; combining the low-intensity magnetic separation rough concentration tailing product and the low-intensity magnetic separation fine concentration tailing product into a low-intensity magnetic separation tailing product, and oxidizing the low-intensity magnetic separation tailing product into Fe₂(SO₄)₃The pyrrhotite of the weakly magnetic minerals becomes a tailing product of the weak magnetic separation.

The primary coarse-fine two-stage continuous low-intensity magnetic separation process is carried out by adopting a conventional low-intensity magnetic separator with the magnetic field intensity of 1500Gs under the condition of conventional ore feeding concentration of 30%, and the results of chemical multi-element analysis, iron matter phase analysis and mineral content analysis of the iron ore concentrate after separation are respectively shown in tables 3 and 4.

Table 3 main chemical composition analysis result (%) -of iron ore concentrate after grading

Components	TFe	mFe	FeO	Fe2O3	SiO2	TiO2	Al2O3	CaO
									Content (wt.)	68.13	67.82	30.97	63.56	4.13	0.29	0.63	0.20
Components	MgO	MnO	Na2O	K2O	P	S	C	Loss of heat
									Content (wt.)	0.19	0.09	0.04	0.05	0.01	0.09	0.01	0.3

Table 4 chemical phase analysis result (%) -of iron in iron ore concentrate after grading

If the ore feeding granularity of the high-sulfur magnetite concentrate is fine enough, the high-sulfur magnetite concentrate can be directly added into a stirring tank for oxidation reaction without closed circuit ore grinding operation, and then the pyrrhotite is removed by adopting a low-intensity magnetic separation process.

In addition, for the mineral separation process of the high-sulfur magnetite ore with sulfur content not exceeding a lot, a strong oxidant can be added in the ore grinding operation before concentration to remove a part of pyrrhotite, so as to ensure that the sulfur content of the iron ore concentrate is qualified.