Resource utilization method of low-grade refractory tin-containing tailings

Abstract

The invention discloses a resource utilization method of low-grade refractory tin-containing tailings, and belongs to the technical field of solid waste resource utilization. The method comprises the following steps: uniformly mixing the low-grade refractory tin-containing tailings with a fluorine-containing calcium compound, an alkalinity regulator and a carbonaceous reducing agent, then carrying out reduction roasting, recovering a tin product from roasting flue gas, and using the remaining roasting tailings as a cementing material. By means of the method, tin in the low-grade tin-containing tailings can be efficiently recycled, the tailings obtained after tin is recycled can be used for preparing the cementing material with the high additional value, and resource utilization of the tailings is achieved.

Description

Technical Field

[0001] The invention relates to a method for treating low-grade and difficult-to-select tin-containing tailings, and in particular to a method for recovering tin from low-grade and difficult-to-select tin-containing tailings and for resource utilization of roasting tailings, belonging to the technical field of resource utilization of bulk mine solid wastes. Background Art

[0002] In my country, tin-containing polymetallic mineral resources are abundant, and most of them belong to skarn-type deposits, which are distributed in Inner Mongolia, Hunan, Guangdong and Guangxi. Such deposits are mostly associated with tungsten, tin, antimony, zinc, iron and other elements. Although the grade of tin has exceeded the minimum grade that can be mined (0.1-0.2%), a large number of studies have shown that the tin minerals in such tin-containing deposits are mainly cassiterite, which is mostly embedded in fluorite or silicate in the form of medium-fine or coarse aggregates. A few are replaced by magnetite, sphalerite and arsenopyrite in the gangue, or appear as fine veins and fine vein impregnation. They are mostly distributed between calcium iron pyroxene and calcium iron garnet particles and in cracks. There are many types of minerals and complex co-existence relationships, which makes it extremely difficult to efficiently recover and utilize cassiterite resources. Through conventional mineral processing, the amount of tailings discarded is huge and the processing cost is high. Therefore, it is very urgent to find a suitable method for recovering cassiterite resources in view of this situation.

[0003] A Chinese invention patent (publication number CN113731628A) discloses a method for efficiently recovering cassiterite from fine-grained disseminated tin polymetallic ores, emphasizing separation through conventional multiple beneficiation processes, wherein coarse-grained intermediates and tin intermediates are re-grinded and re-selected intermediates are returned to their respective grinding operations in turn, forming a large grinding-reselection cycle. Although qualified tin concentrates and tailings are finally produced, the process is complicated and the procedures are cumbersome. A Chinese invention patent (publication number CN 115155824 A) discloses a method for recovering tin from tin-containing fine mud, emphasizing the use of technical means in the field of mineral processing to process and recover cassiterite, but the process of the method is becoming increasingly complicated, and the flotation reagent system used is intensive. Although the comprehensive recovery rate of tin obtained by the treatment can reach more than 80%, there are still a large number of tailings that have not been processed. A Chinese invention patent (publication number CN 102965522 A) discloses a method for separating and recovering tin from tin-containing tailings in ore dressing. For low-grade tin-containing tailings that are difficult to be processed by traditional ore dressing processes, a method for roasting and volatilizing tin in a weak reducing atmosphere is adopted. The tin volatilization rate mentioned in the invention is only 70-80%, the recovery efficiency is not high, and the subsequent treatment of tailings is less mentioned. A Chinese patent (publication number CN 118222834 A) discloses a method for resource utilization of garnet-type tin-containing tailings. The method specifically comprises mixing garnet-type tin-containing tailings with an alkalinity adjuster and a carbonaceous reducing agent, performing reduction roasting in an oxygen-free atmosphere, recovering tin products from the roasting flue gas, and using the remaining roasting tailings for composite silicate cement or cementitious materials. The tin recovery rate of this method is not ideal, and the resulting roasting tailings can only be used as a composite silicate cement admixture, or in combination with PO425 cement, desulfurized gypsum, etc. to prepare cementitious materials. The amount of the tailings in cement or cementitious materials is low, making it difficult to achieve large-scale application.

[0004] Therefore, finding a way to efficiently process low-grade, difficult-to-select tin-containing tailings, recover valuable tin resources, and dispose of the roasted slag for resource utilization can not only meet the development requirements of green mines, but also significantly improve social, economic and environmental benefits. Summary of the invention

[0005] In view of the technical problems in the prior art such as low recovery efficiency of valuable metal elements in low-grade and difficult-to-select tin-containing tailings and low resource utilization rate of tailings, the purpose of the present invention is to provide a method for resource utilization of low-grade and difficult-to-select tin-containing tailings, which can not only efficiently recover tin from the low-grade tin-containing tailings, but also use the tailings slag after tin recovery to prepare a cementitious material with high added value, thereby realizing resource utilization of tailings.

[0006] In order to achieve the above technical objectives, the present invention provides a method for resource utilization of low-grade and difficult-to-select tin-containing tailings, which comprises mixing the low-grade and difficult-to-select tin-containing tailings with a fluorine-containing calcium compound, an alkalinity adjuster and a carbonaceous reducing agent, and then performing reduction roasting, recovering the tin product from the roasting flue gas, and using the remaining roasting tailings for cementitious materials.

[0007] The present invention conducts a high-temperature reduction reaction on low-grade and difficult-to-select tin-containing tailings in the presence of a carbonaceous reducing agent, a fluorine-containing calcium compound and an alkalinity adjusting agent. In the high-temperature reduction process, the carbonaceous reducing agent, on the one hand, promotes the volatilization of tin, mainly by reducing the high-boiling-point SnO2 in the tailings into SnO with a relatively low boiling point, thereby promoting the volatilization and recovery of tin, and on the other hand, provides a reducing environment for the roasting process; the fluorine-containing calcium compound is used as a mineralizer, which can not only serve as a calcium source to promote and supplement the clinkering reaction effect and element deficiency of the tailings components during high-temperature roasting, but also play a good mineralization effect, enhance the clinkering degree of silicate minerals in a relatively low temperature range (900-1150° C.) during the tailings roasting process, and improve the volcanic ash activity of the roasting tailings; and the alkalinity adjusting agent can improve the volatilization effect of tin by adjusting the alkalinity of the tailings, thereby obtaining a higher tin volatilization recovery rate.

[0008] As a preferred solution, the mass ratio of the low-grade refractory tin-containing tailings to the fluorine-containing calcium compound, the alkalinity adjuster and the carbonaceous reducing agent is 100:5 to 10:5 to 10:1 to 8. The introduction ratio of the fluorine-containing calcium compound, the alkalinity adjuster and the carbonaceous reducing agent has a relatively large influence on the volatilization recovery efficiency of tin in the low-grade refractory tin-containing tailings during high-temperature reduction roasting and the maturation process of other minerals. More specifically, the amount of carbonaceous reducing agent should not be too high. Since the tin grade in low-grade and difficult-to-select tin-containing tailings is low, it is not appropriate to set too high a reducing agent amount within the designed temperature range. This is mainly to avoid the strong reducing atmosphere causing the magnetite in the tin-containing tailings to react with cassiterite to produce an iron-tin alloy, which causes the tin to be unable to volatilize, thereby reducing the tin recovery rate. The amount of carbonaceous reducing agent should not be too low, which will cause SnO2 to be difficult to convert into SnO with a relatively low boiling point, thereby affecting the tin volatilization rate. At the same time, the carbonaceous reducing agent also has the effect of promoting the reconstruction of other mineral crystal forms. If its content is too low, it will reduce the difficulty of fully maturing the tailings components and reduce their volcanic ash activity. The mass ratio of the low-grade and difficult-to-select tin-containing tailings to the carbonaceous reducing agent is further preferably 100:1.5~5. Fluorine-containing calcium compounds are introduced as important mineralizers. The calcium element as a calcium source is beneficial to the conversion of silicate minerals in low-grade and difficult-to-select tin-containing tailings into highly volcanic ash-active minerals. The fluorine element as a good mineralizing component can reduce the melting temperature during the tailings roasting process, while promoting the clinkering reaction between the calcium element and the silicate minerals. In addition, the molten state formed is agitated by gases such as carbon dioxide and carbon monoxide in a reducing atmosphere, which reduces the gas volatilization path and is beneficial to the reduction and volatilization of tin. Therefore, if the introduction ratio of fluorine-containing calcium compounds is too low, it will be unfavorable for the volatilization recovery of tin and the maturation of minerals in low-grade and difficult-to-select tin-containing tailings, while an excessively high ratio will make it easier to form a molten phase during the high-temperature calcination process, resulting in melting or bonding of the calcined material, affecting the fluidity and structure of the material. The alkalinity adjuster can react with silicon dioxide (SiO2) in fluorine-containing calcium compounds to increase the alkalinity of the silicon-containing mineral reaction clinkering and generate calcium silicate (CaSiO3), thereby removing SiO2. This process reduces the impurity content in the reduction reaction. At the same time, the calcium silicate slag generated helps to reduce the viscosity of the slag, making it easier for the tin in it to volatilize and discharge. In addition, calcium oxide can also adjust the temperature gradient in the blast furnace, reduce erosion in high-temperature areas, increase the fluidity of the slag, promote material mixing and dispersion, and ensure the uniformity of the reaction. Therefore, the use of an appropriate amount of alkalinity adjuster is very beneficial for the volatilization of tin and the maturation of minerals.

[0009] As a preferred solution, the low-grade refractory tin-containing tailings contain quartz, feldspar, garnet, calcium iron pyroxene and magnetite, wherein the silicate mineral mass content is greater than 75%, and the tin grade is 0.16-0.35%. Based on the characteristics of high silicate mineral content, low tin grade, and a small amount of magnetite in the low-grade refractory tin-containing tailings, it is determined that a high proportion of fluorine calcium compounds, alkalinity adjusters, and a relatively low proportion of carbonaceous reducing agents need to be added during the high-temperature reduction roasting process to ensure efficient volatilization and recovery of tin, while achieving sufficient maturation of the residual tailings and improving its volcanic ash activity.

[0010] As a preferred solution, the fluorine-containing calcium compound includes at least one of monofluoro calcium phosphate, fluoro calcium phosphate, and fluoro calcium silicate. The preferred fluorine-containing calcium compound contains both calcium and fluorine. The calcium element as a calcium source can convert minerals such as silicates or silicon dioxide into calcium silicates with volcanic ash activity, while the fluorine element can play a good mineralization effect, enhance the clinkering degree of silicate minerals in the lower temperature range (900-1150°C) during the tailings roasting process, and improve the volcanic ash activity of the roasting tailings.

[0011] As a preferred solution, the carbonaceous reducing agent includes at least one of anthracite, bituminous coal, blue carbon and coke. On the one hand, the carbonaceous reducing agent can reduce the high-boiling-point SnO2 in the tailings to SnO with a relatively low boiling point at high temperature, thereby promoting the volatilization and recovery of tin, and on the other hand, the carbonaceous reducing agent provides a reducing environment for the roasting process.

[0012] As a preferred solution, the alkalinity adjuster includes calcium oxide. The present invention preferably uses calcium oxide as an alkalinity adjuster, which can react with silicon dioxide (SiO2) in the tailings, increase the alkalinity of the silicon-containing mineral reaction clinker, generate calcium silicate (CaSiO3), and thus remove SiO2. This process reduces the impurity content in the reduction reaction, and the calcium silicate slag generated helps to reduce the viscosity of the slag, making it easier for the tin therein to volatilize and discharge. In addition, calcium oxide can also adjust the temperature gradient in the blast furnace, reduce the erosion in the high-temperature area, and increase the fluidity of the slag, promote material mixing and dispersion, and ensure the uniformity of the reaction.

[0013] As a preferred solution, the reduction roasting conditions are: from room temperature to 900-1150°C, and keep warm for 30-60 minutes. In the preferred reduction roasting process, the tin dioxide mineral can be reduced to SnO, and enter the flue gas in the form of gas, and then form solid SnO2 and Sn through disproportionation reaction. At the same time, in a high temperature environment and under the reduction effect of a carbonaceous reducing agent, the silicate minerals in the tailings can be promoted to achieve mineral reconstruction, and the roasting tailings with volcanic ash activity can be converted, so that it can be used to prepare cementitious materials. The reduction roasting conditions are further preferably: from room temperature to 950-1050°C, and keep warm for 35-60 minutes.

[0014] As a preferred solution, the roasting tailings and the activator are activated and then mixed with the slag powder to obtain a cementitious material. The roasting tailings and the activator are mixed and activated by high-energy ball milling. The high-energy ball milling is used to control the specific surface area of ​​the ball milled material to 760±10m 2 / kg.

[0015] As a preferred solution, the activator comprises anhydrous sodium silicate with a modulus of 1.4 to 3.4; the mass of the activator is 15 to 30% of the mass of the roasting tailings.

[0016] As a preferred solution, the roasting tailings and the slag powder are mixed in a mass percentage of 50-80%:20-50%. The roasting tailings of the present invention have high volcanic ash activity, which greatly increases the amount of roasting tailings added.

[0017] As a more preferred solution, the slag powder is commercially available grade S95.

[0018] The method for resource utilization of low-grade and difficult-to-select tin-containing tailings provided by the present invention comprises the following steps:

[0019] (1) Recovering tin from low-grade and difficult-to-select tin-containing tailings: The low-grade and difficult-to-select tin-containing tailings are filtered and dried, and mixed evenly with a carbonaceous reducing agent, a fluorine-containing calcium compound and an alkalinity adjusting agent in a mixer, and then the mixed material is reduced and roasted in a tubular vacuum furnace. The roasting process is to heat the temperature from room temperature to a preset temperature of 900 to 1150° C., and then keep the temperature at the preset temperature for 30 to 60 minutes. The tubular vacuum furnace is continuously introduced with a protective gas (preferably argon gas with a purity of >99%), and the gas flow rate should ensure that the roasting process is an oxygen-free environment. The smoke dust converted from the volatilized gaseous tin is recovered by a smoke dust collection system.

[0020] (2) Preparation of cementitious materials by resource utilization of roasted tailings slag: Add roasted tailings slag and activator into a planetary ball mill, the ball mill speed is 600r / min, the powder is ground and activated for 60min, and the medium filling rate is 18.5%. The activated tailings slag and slag powder are mixed evenly to obtain cementitious materials; wherein, the mass ratio of roasted tailings to slag powder is calculated according to the mass of slag powder replacing roasted tailings, that is, 20-50%; the amount of activator is 15-30wt% of the mass of roasted tailings.

[0021] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0022] 1. Aiming at the occurrence form and mineral composition of tin in low-grade and difficult-to-select tin-containing tailings, high-temperature reduction roasting treatment can not only realize high-value recovery of metal resources by volatilization recovery of tin, but also realize phase reconstruction of silicate minerals in tailings to obtain clinker with high volcanic ash to realize resource utilization of tailings, forming a closed loop of tailings-free emission mode for mining enterprises, which not only creates new economic benefits, but also solves the problems of solid waste utilization and environmental pollution in mines, with significant social and environmental benefits.

[0023] 2. The low-grade and difficult-to-select tin-containing tailings used in the present invention contain silicate minerals greater than 75%. During the high-temperature reduction roasting process for recovering tin, by adding fluorine-containing calcium compounds as mineralizers, the low-temperature clinkering degree can be enhanced, further improving the volcanic ash activity of the tailings slag after roasting.

[0024] 3. The key to the high-temperature roasting process of low-grade and difficult-to-select tin-containing tailings in the present invention is the use of a carbonaceous reducing agent, a fluorine-containing calcium compound and an alkalinity adjuster. The carbonaceous reducing agent plays a reducing role and can promote the reduction of tin dioxide minerals in the tailings to stannous oxide with a lower boiling point. The fluorine-containing calcium compound strengthens and supplements the tailings roasting clinker process and elements, and promotes the reconstruction of silicate minerals in the tailings under the action of the alkalinity adjuster, thereby improving the degree of clinkerization and giving the roasting tailings a higher volcanic ash activity. The alkalinity regulator can enhance the volatilization effect of tin by adjusting the alkalinity of the tailings, thereby obtaining a higher tin volatilization recovery rate, and the tin recovery rate can reach more than 95%.

[0025] 4. The present invention aims to realize the comprehensive utilization of tailings and further utilizes the tailings slag after roasting, which not only achieves the goal of tailings-free mines, but also expands the utilization field of building materials resources. By simplifying the preparation process of cementitious materials, the prepared cementitious materials are used as geopolymers for underground filling cementitious materials in mines, which feeds back to the mine's self-production and self-sales model, greatly utilizing the mine's own resource advantages, realizing efficient resource utilization of solid waste, having obvious application value, and remarkable economic and social benefits. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with a specific embodiment, but the protection scope of the claims is not limited to this embodiment.

[0027] The chemical reagents involved in the following specific examples are conventional industrial reagents unless otherwise specified.

[0028] In the following specific embodiments, the low-grade and difficult-to-select tin-containing tailings used have a main chemical composition of SiO2 37.85wt%, Al2O3 10.40wt%, CaO 20.17wt%, Fe2O3 25.66wt%, and a tin grade of 0.20-0.50%.

[0029] Example 1

[0030] A method for recovering tin from low-grade and difficult-to-select tin-containing tailings and its resource utilization comprises the following steps:

[0031] (1) Recovery of tin from tailings: The tailings are filtered and dried, and mixed evenly with 1.5% bituminous coal, 8.6% calcium fluorophosphate, and 6.5% calcium oxide in a mixer, and the mixture is roasted in a tubular vacuum furnace. The roasting process is to heat the temperature from room temperature to a preset temperature of 955°C, and then keep it at a preset temperature for 35 minutes. The protective gas argon is continuously introduced into the tubular vacuum furnace, and the gas flow rate ensures that the roasting process is an oxygen-free environment. The volatilized tin is recovered by a flue gas dust collection system into which oxygen is introduced. The recovery rate of tin is shown in Table 5.

[0032] (2) Preparation of cementitious material from calcined tailings slag: In a planetary ball mill, add calcined tailings slag and an activator, wherein the modulus of sodium silicate is 2.3, the amount of the activator is 25%, the ball mill speed is 600 r / min, the medium filling rate is 18.5%, and the powder is activated for 60 minutes. Then, the activated tailings slag and slag powder are evenly mixed in a weight ratio of 70:30 to obtain a cementitious material for underground mine filling.

[0033] Example 2

[0034] The differences from Example 1 are shown in Tables 1 and 2.

[0035] Example 3

[0036] The differences from Example 1 are shown in Tables 1 and 2.

[0037] Example 4

[0038] The differences from Example 1 are shown in Tables 1 and 2.

[0039] Comparative Example 1

[0040] Conventional commercially available adhesive powder was used as a control.

[0041] Comparative Example 2

[0042] The difference from Example 2 is that:

[0043] The slag powder is replaced by the roasting tailings in the cement powder raw material, and then mixed evenly with the activator.

[0044] Comparative Example 3

[0045] The differences from Example 3 are shown in Tables 1 and 2.

[0046] Comparative Example 4

[0047] The differences from Example 4 are shown in Tables 1 and 2.

[0048] Comparative Example 5

[0049] The differences from Example 2 are shown in Tables 1 and 2.

[0050] Table 1 Composition and conditions of reduction roasting raw materials

[0051] name SnO2 grade / % Reducing agent type Reducing agent dosage / % Mineralizer Type Mineralizer dosage / % Calcium oxide / % Calcination temperature / ℃ Insulation time / min Example 1 0.22 bituminous coal 1.5 Calcium fluorophosphate 8.6 6.5 955 35 Example 2 0.26 Blue Coke 5 Calcium Fluorosilicate 9.7 8.1 975 60 Example 3 0.18 Coke 2.4 Calcium monofluorophosphate 5.4 9.4 1050 41 Example 4 0.32 Coke 3.1 Calcium fluorophosphate 6.5 5.7 963 50 Comparative Example 3 0.18 Coke 2.4 / / 9.4 1050 41 Comparative Example 4 0.32 Coke 3.1 Calcium fluorophosphate 6.5 / 965 50 Comparative Example 5 0.26 Blue Coke 15 Calcium Fluorosilicate 9.7 8.1 975 60

[0052] Table 2 Composition of raw materials of cementitious materials in Examples and Comparative Examples

[0053] name Roasting tailings / % Slag powder / % Sodium silicate modulus Sodium silicate dosage / % Example 1 70 30 2.3 25 Example 2 76 24 1.4 30 Example 3 64 36 2.3 18 Example 4 57 43 2.8 22 Comparative Example 2 0 100 1.4 30 Comparative Example 3 64 36 2.3 18 Comparative Example 4 57 43 2.8 22 Example 5 76 24 1.4 30

[0054] Performance Testing

[0055] The compressive strength and fluidity tests were performed on Examples 1 to 4 and Comparative Examples 1 to 5, respectively. Fluorite beneficiation tailings were used for the test, with a concentration of 73.5%. The method was carried out in accordance with GB / T 20100972-T-609 and GB / T 31289-2014 for comparative tests. A 40×40×40mm triple test mold was used for the compressive strength mold. The tin volatilization rate of Examples 1 to 4 was tested. The test results are shown in Table 3 below.

[0056] Table 3 Performance test results and tin volatilization rate

[0057]

[0058] The test results show that the volatilization rate of tin in the embodiments of the present invention under the conditions of reduction roasting is greater than 95%. Increasing the amount of reducing agent does not increase the volatilization rate of tin, but reduces it, because excessive reducing agent will lead to incomplete reaction and produce undesirable by-products. For example, during the reduction process, excessive reducing agent may react with oxides or other reactants to generate gaseous or solid by-products, such as hydrogen, carbides or other impurities, which affect the purity of the product. The performance of the cementitious material prepared after adding roasting tailings is better than that of comparative example 2, indicating that after mineralization roasting, the activity of the tailings increases significantly. The results of comparative examples 2 and 3 also show that in the absence of the action of mineralizer, the effect of tailings roasting clinkerization becomes worse, which affects its reaction activity and also has a certain weakening effect on the volatilization rate. The method implemented by the present invention not only efficiently recycles valuable resources, but also utilizes and processes the remaining solid waste in large quantities. For mining enterprises, it not only increases the efficiency of new products, but also meets the needs of energy conservation and consumption reduction, and realizes the goal of developing and building green mines. It has promotion and reference significance for many mining enterprises.

[0059] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A method for resource utilization of low-grade difficult-to-select tin-containing tailings, characterized in that: The low-grade and difficult-to-select tin-containing tailings are mixed with fluorine-containing calcium compounds, alkalinity adjusters and carbonaceous reducing agents and then reduced and roasted. The tin product is recovered from the roasting flue gas, and the remaining roasting tailings are used as cementitious materials.

2. A method for resource utilization of low-grade, difficult-to-select tin-containing tailings according to claim 1, characterized in that: The mass ratio of the low-grade difficult-to-select tin-containing tailings to the fluorine-containing calcium compound, the alkalinity adjuster and the carbonaceous reducing agent is 100:5-10:5-10:1-8.

3. A method for resource utilization of a low-grade, difficult-to-select tin-containing tailings according to claim 1 or 2, characterized in that: The low-grade and difficult-to-select tin-containing tailings contain quartz, feldspar, garnet, calcium-iron pyroxene and magnetite, wherein the silicate mineral mass content is greater than 75%, and the tin grade is 0.16-0.35%.

4. A method for resource utilization of low-grade, difficult-to-select tin-containing tailings according to claim 1 or 2, characterized in that: The fluorine-containing calcium compound includes at least one of calcium monofluorophosphate, calcium fluorophosphate and calcium fluorosilicate.

5. A method for resource utilization of low-grade, difficult-to-select tin-containing tailings according to claim 1 or 2, characterized in that: The carbonaceous reducing agent includes at least one of anthracite, bituminous coal, semi-coke and coke.

6. A method for resource utilization of low-grade, difficult-to-select tin-containing tailings according to claim 1 or 2, characterized in that: The alkalinity adjuster includes calcium oxide.

7. A method for resource utilization of low-grade, difficult-to-select tin-containing tailings according to claim 1 or 2, characterized in that: The reduction roasting conditions are: rising from room temperature to 900-1150° C. and keeping the temperature for 30-60 minutes.

8. The method for resource utilization of low-grade and difficult-to-select tin-containing tailings according to claim 1, characterized in that: The roasting tailings and the activator are activated and then evenly mixed with the slag powder to obtain the cementitious material.

9. The resource utilization method of a low-grade and difficult-to-select tin-containing tailings according to claim 8, characterized in that: The activator comprises anhydrous sodium silicate with a modulus of 1.4 to 3.4; the mass of the activator is 15 to 30% of the mass of the roasting tailings.

10. The method for resource utilization of low-grade and difficult-to-select tin-containing tailings according to claim 8, characterized in that: The roasting tailings and the slag powder are mixed in a mass percentage of 50-80%:20-50%.

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