Method for comprehensively utilizing low-grade micro-fine particle tungsten tin

Abstract

The invention discloses a method for comprehensively utilizing low-grade micro-fine particle tungsten tin, and relates to the technical field of mineral processing, an advanced flotation equipment system and a beneficiation reagent are used, and the method comprises the following steps that raw ore tungsten tin is subjected to concentration, reagent adding, stirring and pumping to desulfurization operation, and the desulfurization operation adopts a one-time roughing and one-time concentration process; and the desulfurized tailings enter a tungsten-tin flotation process, the tungsten-tin flotation process adopts one-time roughing, two-time concentration and two-time scavenging processes, and finally comprehensive recycling of the low-grade micro-fine particle tungsten tin is achieved. When the raw ore is low in grade (WO3 is 0.20%-0.40%, and Sn is 0.10%-0.30%), WO3 + Sngt can be obtained; the tungsten recovery rate is not less than 76%, and the tin recovery rate is not less than 59%. The method is simple in equipment, low in medicament cost, capable of being suitable for comprehensive recycling of similar low-grade micro-fine particle tungsten tin, considerable in economic benefit and environmental benefit and remarkable in advantage compared with the prior art, the economic benefit of enterprises is improved, and resource waste is reduced.

Description

[Technical field]

[0001] The invention relates to the technical field of mineral processing, and in particular to a method for comprehensive utilization of low-grade fine tungsten-tin particles. [Background technology]

[0002] Tungsten-tin has good physical and chemical properties and is a strategically important metal resource, which is widely used in alloy materials, semiconductors, aerospace and other fields. In the black and white tungsten paragenetic deposits, tungsten ore is often associated with cassiterite, with fine embedded particles and complex mineral composition. It is a typical refractory ore type and difficult to separate.

[0003] The Chinese patent with publication number CN116060204A discloses a new process for the efficient and rapid selection of blanket tungsten-tin fine mud. The process passes the raw ore through a large-pitch spiral chute, a medium-pitch spiral chute, and a small-pitch spiral chute for re-selection and roughing. A hydraulic classification shaking table system is used to classify the incoming materials in the spiral chute and transport them to different shaking tables for processing. Different slots of the shaking table are used to recover ore materials of different particles. However, this method is more suitable for general coarse-grained tungsten-tin mixed ores, and it is still difficult to effectively separate low-grade fine-particle embedded tungsten-tin mixed ores. Low-grade fine-particle embedded tungsten-tin mixed ores are generally recovered by flotation.

[0004] Due to the large fluctuation of the grade of low-grade fine-particle tungsten and tin, and the fact that all the particles processed by flotation are fine particles, which have the characteristics of small mass and large specific surface area, the application of traditional flotation equipment is subject to certain restrictions, affecting the final grade and recovery rate of the metal.

[0005] The Chinese patent with publication number CN111495579A discloses a method for recovering tungsten and tin from fine mud sand. The method subjects the fine mud sand to be selected to flotation desulfurization roughing-scavenging, tungsten-tin mixed flotation roughing-scavenging, magnetic roughing-concentrating, and flotation separation roughing-concentrating operations, and finally obtains scheelite concentrate and tin concentrate. The Chinese patent with publication number CN107617508A discloses a beneficiation process for fine-grained tungsten-tin co-existing ore. The process adopts the process of gravity separation tailing pre-selection, reverse flotation desulfurization and desiliconization, and magnetic separation to separate wolframite and cassiterite. The above-disclosed prior art has certain limitations. When using traditional flotation equipment and reagent system, the fine particle size is difficult to be effectively recovered, resulting in low system recovery rate, low concentrate grade, poor sorting effect, and relatively low processing capacity. In addition, the current process used for low-grade fine tungsten tin is complex and the process is cumbersome, which is not conducive to its industrial promotion and application.

[0006] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. [Summary of the invention]

[0007] In view of the shortcomings of the existing technology for comprehensive utilization and recovery of fine-grained tungsten and tin, the present invention proposes a method for comprehensive utilization of low-grade fine-grained tungsten and tin, which adopts new flotation equipment and mineral processing agents to greatly improve the grade and recovery rate of tungsten and tin.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for comprehensive utilization of low-grade fine tungsten-tin particles, using advanced flotation equipment systems and mineral processing reagents;

[0010] The advanced flotation equipment system includes a thickener, a desulfurization roughing flotation column, a desulfurization fine flotation column, a tungsten-tin roughing flotation column, a tungsten-tin sweeping flotation column, a tungsten-tin sweeping flotation column, a tungsten-tin fine flotation column, a tungsten-tin fine flotation column and a slurry stirring barrel equipped with each.

[0011] Furthermore, the discharge port of the thickener is connected to the feed port of the desulfurization roughing mixing barrel; the desulfurization roughing mixing barrel is connected to the feed port of the desulfurization roughing flotation column through a pipeline, the concentrate overflow port of the desulfurization roughing flotation column is connected to the desulfurization and selection mixing barrel through a pipeline, and the tailings underflow port of the desulfurization roughing flotation column is connected to the tungsten-tin roughing mixing barrel through a pipeline; the desulfurization and selection mixing barrel is connected to the feed port of the desulfurization and selection flotation column through a pipeline, and the concentrate overflow port of the desulfurization and selection flotation column is transported to the pump through a pipeline The tailings bottom flow outlet of the desulfurization and concentration flotation column is returned to the desulfurization roughing mixing barrel through a pipeline; the tungsten-tin roughing mixing barrel is connected to the feed inlet of the tungsten-tin roughing flotation column through a pipeline, and the concentrate overflow outlet of the tungsten-tin roughing flotation column is connected to the tungsten-tin concentration mixing barrel through a pipeline, and the tailings bottom flow outlet of the tungsten-tin roughing flotation column is connected to the tungsten-tin scavenging mixing barrel through a pipeline; the tungsten-tin scavenging mixing barrel is connected to the feed inlet of the tungsten-tin scavenging flotation column through a pipeline, and the concentrate overflow outlet of the tungsten-tin scavenging flotation column is connected to the tungsten-tin scavenging flotation column through a pipeline. The tailings outlet of the first flotation column of tungsten-tin scavenging is connected to the stirring barrel of the second tungsten-tin scavenging through a pipeline; the stirring barrel of the first tungsten-tin scavenging is connected to the feeding port of the first flotation column of tungsten-tin scavenging through a pipeline; the overflow port of the first flotation column of tungsten-tin scavenging is connected to the stirring barrel of the second tungsten-tin scavenging through a pipeline; the tailings outlet of the first flotation column of tungsten-tin scavenging is returned to the stirring barrel of the roughing through a pipeline; the stirring barrel of the second tungsten-tin scavenging is connected to the feeding port of the second flotation column of tungsten-tin scavenging through a pipeline. The two flotation columns are connected by pipelines, the concentrate overflow port of the second flotation column of tungsten-tin scavenging is connected to the first stirring barrel of tungsten-tin scavenging through pipelines, and the tailings underflow port of the second flotation column of tungsten-tin scavenging is transported to the thickener through pipelines for thickening and then to the tailings pump pool; the second stirring barrel of tungsten-tin selection is connected to the feed port of the second flotation column of tungsten-tin selection through pipelines, the concentrate overflow port of the second flotation column of tungsten-tin selection is transported to the tungsten-tin concentrate pump pool through pipelines, and the tailings underflow port of the second flotation column of tungsten-tin selection is returned to the first stirring barrel of tungsten-tin selection through pipelines.

[0012] Furthermore, each mixing barrel of the desulfurization roughing flotation column, desulfurization fine flotation column, tungsten-tin roughing flotation column, tungsten-tin sweeping flotation column, tungsten-tin sweeping flotation column, tungsten-tin fine flotation column, tungsten-tin fine flotation column is respectively provided with a feeding pump to transport the slurry to the corresponding flotation column feed port.

[0013] Furthermore, the desulfurization roughing flotation column, desulfurization fine flotation column, tungsten-tin roughing flotation column, tungsten-tin sweeping flotation column, tungsten-tin sweeping flotation column, tungsten-tin fine flotation column, tungsten-tin fine flotation column are respectively provided with self-circulating pumps.

[0014] Furthermore, the mineral processing reagents include a regulator, a collector and a frother.

[0015] Furthermore, the above-mentioned mineral processing reagents are added to the ore pulp in a certain amount at each operation stage of tungsten-tin desulfurization and tin-tungsten mixed flotation. The types and amounts of mineral processing reagents added at each operation stage are as follows:

[0016] Desulfurization stage:

[0017] Copper sulfate is used as an adjusting agent for activation, and its dosage is 50-150g / t;

[0018] Use 2# oil as foaming agent for foaming, and its dosage is 2-30g / t;

[0019] Butyl xanthate is used as a collector for sulfide ore collection, and its dosage is 30-200g / t.

[0020] Mixed flotation stage:

[0021] Sodium carbonate is used as an adjusting agent to soften water and adjust the pH of the slurry, with a dosage of 300-900g / t;

[0022] Lead nitrate is used as a regulator to activate tungsten and tin, with a dosage of 150g-450g / t;

[0023] Acidified water glass is used as a regulator to suppress iron impurities and silicates, with a dosage of 30-300g / t;

[0024] GY-1 with excellent tungsten-tin capture and selectivity is used as a tungsten-tin collector to capture tungsten-tin, and its dosage is 10-200g / t. GY-2 is used as an auxiliary tungsten-tin collector, and its dosage is 1-10g / t.

[0025] A method for comprehensive utilization of low-grade fine tungsten-tin particles comprises the following steps:

[0026] Step (1): Concentration: The low-grade fine-grained tungsten-tin ore slurry is concentrated by a thickener;

[0027] Step (2): Desulfurization: After concentration, the low-grade fine-grained tungsten-tin slurry is desulfurized by a desulfurization flotation column; the underflow slurry of the thickener 1 is mixed with a regulator, a collector, and a frother by a desulfurization roughing mixing barrel, and the slurry after the addition of the regulator is fed into the desulfurization roughing flotation column by a feed pump, the concentrate of the desulfurization roughing flotation column flows into the desulfurization concentration flotation column, and the tailings of the desulfurization roughing flotation column are fed into a tungsten-tin roughing mixing barrel, and the regulator and collector are added to mix the slurry, and then fed into the tungsten-tin roughing flotation column by a feed pump;

[0028] Step (3): Mixed flotation: After desulfurization, the low-grade fine tungsten-tin ore pulp is subjected to tin-tungsten mixed flotation through each operating flotation column; the concentrate of the tungsten-tin roughing flotation column flows into the tungsten-tin selection first stirring barrel, and the adjusting agent is added to adjust the slurry, and then fed into the tungsten-tin selection first flotation column through the feeding pump; the tailings of the tungsten selection roughing flotation column are fed into the tungsten-tin scavenging selection first stirring barrel, and the adjusting agent and collector are added to adjust the slurry, and then fed into the tungsten-tin scavenging selection first flotation column through the feeding pump; the concentrate of the tungsten-tin selection first flotation column flows into the tungsten-tin selection second stirring barrel, and the collector is added to adjust the slurry, and then fed into the tungsten-tin selection second flotation column through the feeding pump, and the tailings of the tungsten-tin selection first flotation column are returned to the tungsten-tin selection second flotation column. The roughing mixing barrel realizes closed-loop circulation; the concentrate of the tungsten-tin scavenging flotation column No. 1 is returned to the tungsten-tin roughing mixing barrel, and the tailings of the tungsten-tin scavenging flotation column No. 1 is fed into the tungsten-tin scavenging mixing barrel No. 2 to add the collector to adjust the slurry, and then fed into the tungsten-tin scavenging flotation column No. 2 through the feed pump; the concentrate of the tungsten-tin scavenging flotation column No. 2 is returned to the tungsten-tin scavenging mixing barrel No. 1, and the tailings of the tungsten-tin scavenging flotation column No. 2 enters the thickener and flows into the tailings pump pool and is pumped away; the concentrate of the tungsten-tin concentration flotation column No. 2 flows into the tungsten-tin concentrate pump pool and is pumped away, and the tailings of the tungsten-tin concentration flotation column No. 2 returns to the tungsten-tin concentration mixing barrel No. 1, realizing closed-loop circulation and producing tungsten-tin mixed concentrate.

[0029] The technical principles and beneficial effects of the present invention include:

[0030] 1. Technical Principle

[0031] 1. Principle of flotation equipment system:

[0032] In the beneficiation process of low-grade fine-grained tungsten-tin ore, the thickener, as a key pretreatment equipment, shoulders the important task of regulating the pulp concentration. In view of the uneven concentration and complex composition of the original pulp, it is difficult to directly adapt to the subsequent flotation operation. With the help of the gravity sedimentation efficiency of the thickener, the pulp can be efficiently concentrated inside it. After the pulp flows into the thickener, the solid particles gradually settle to the bottom under the action of gravity, and the water continues to overflow and discharge upward, so as to accurately control the pulp concentration in the ideal range of 30%-50%. The precise setting of this concentration range has a far-reaching impact on the subsequent flotation results. When the concentration is low, it is difficult for the flotation reagent to fully contact with the ore particles and react chemically, resulting in a significant reduction in flotation efficiency; high concentration will lead to increased viscosity of the pulp, poor fluidity, and easy to cause equipment blockage, which is also not conducive to the orderly development of flotation operations.

[0033] The concentrated pulp is then transported to the desulfurization roughing flotation column to officially start the desulfurization process. In this link, copper sulfate, as an adjusting agent, takes the lead in playing a role. With its excellent chemical activity, it can quickly penetrate into the lattice of the sulfide ore, causing the chemical properties of the surface of the sulfide ore to change, the potential to be adjusted, and then effectively activated, laying a solid foundation for the subsequent efficient synergistic reaction with the collector; the 2# oil added later is a typical surfactant, which can quickly reduce the surface tension of the pulp. With the help of mechanical stirring, a large amount of fine, stable and resilient foam is continuously generated. These foams, with their good buoyancy properties, are like a carrier, carrying the activated sulfide ore particles steadily up; then, the butyl xanthate, with its unique chemical affinity for the sulfide ore, accurately adheres to the surface of the sulfide ore, and efficiently captures the sulfide ore through chemical bonding or physical adsorption, achieving the initial separation of the sulfide ore and the tungsten-tin ore.

[0034] The pulp from which the sulfide ore is removed then flows into the rough tungsten-tin flotation column, and the subsequent tungsten-tin sweep flotation column, tungsten-tin sweep flotation column, tungsten-tin refinement flotation column, and tungsten-tin refinement flotation column work together to build a comprehensive and refined flotation system. Between each flotation column, the stirring barrel is responsible for the uniform mixing of the pulp and reagent, and with the help of high-speed stirring, the two are fully blended; the feed pump accurately controls the flow rhythm of the pulp between each flotation column to ensure a stable and efficient transportation process; what is particularly critical is that the self-circulating pump equipped in each flotation column can continuously extract part of the pulp in the column for circulation treatment, thereby strengthening the turbulent state and material mixing degree inside the pulp. In this way, tungsten-tin minerals of different particle sizes and properties, whether they are fine particles to micron-level particles or slightly larger particles; whether they are chemically active categories or relatively inert minerals, can find suitable sorting conditions for themselves in the dynamically optimized flotation environment, and ultimately achieve accurate separation and efficient enrichment.

[0035] 2. Principle of mineral processing reagents:

[0036] In the desulfurization stage, various mineral processing agents perform their respective duties and work together to complete the sorting of sulfide ores. Copper sulfate acts as an activator for sulfide ores. When it is incorporated into the slurry, it quickly ionizes copper ions. With its unique chemical activity, copper ions accurately replace some ions on the surface of the sulfide ore, causing the surface properties of the sulfide ore to change from the original low-activity state to an active state that is easy to react with the collector, laying a solid foundation for the smooth development of subsequent collection operations; 2# oil, as a foaming agent, belongs to the category of surfactants. After being added to the slurry, it can quickly reduce the surface tension of the liquid. Under the synergistic effect of mechanical stirring, a large amount of air is drawn into the slurry. The 2# oil molecules are arranged in order at the gas-liquid interface, wrapping the air bubbles, and promoting the formation of fine and stable foam. These bubbles have good buoyancy and can efficiently carry sulfide ore particles to the surface of the slurry, achieving the purpose of initial separation. Butyl xanthate, as a professional sulfide ore collector, can accurately lock onto sulfide ore due to the strong chemical affinity between sulfur atoms in its molecular structure and sulfide ore, and firmly capture sulfide ore through chemical bonding, physical adsorption and other methods.

[0037] In the mixed flotation stage, sodium carbonate is the first to appear as a key agent for water purification and pH adjustment. The ore pulp usually contains various metal ions and impurities, and sodium carbonate can react chemically with them to cause the impurities to precipitate and achieve the effect of softening the water. At the same time, the pH of the ore pulp is precisely adjusted to create a weakly alkaline environment that fits the flotation characteristics of tungsten and tin minerals, ensuring that the subsequent added agents can maintain good chemical activity and ensure that the flotation reaction is stable and efficient. Lead nitrate acts as an activator for tungsten-tin minerals. It is quickly ionized after being added to the pulp. The generated lead ions are tightly adsorbed on the surface of tungsten-tin minerals, cleverly filling the charge vacancies of the mineral lattice, effectively changing the charge distribution and hydration film thickness on the mineral surface, and significantly improving the natural floatability of tungsten-tin minerals, making it easier to combine with bubbles and float during the flotation process; acidified water glass shoulders the task of inhibiting impurities. For common iron-containing impurities and silicates in the pulp, it can use the polymerization precipitation of silicate ions and the complex reaction with metal ions to firmly bind these impurities, inhibit their floating ability, and cause them to precipitate to the bottom of the pulp, thus fully guaranteeing the purity and quality of tungsten-tin concentrates. As professional tungsten-tin collectors, GY-1 and GY-2 show excellent capture and selectivity for tungsten-tin minerals with their excellent molecular structure design and chemical activity. They can accurately identify active sites on the surface of tungsten-tin minerals, efficiently adhere to the tungsten-tin minerals through chemical bonding, physical adsorption and other multiple methods, escort them to float smoothly, break through the numerous obstacles of gangue minerals, achieve accurate separation of tungsten-tin and other gangue minerals, and effectively improve the grade and recovery rate of tungsten-tin.

[0038] 2. Beneficial Effects

[0039] 1. Improve resource utilization: In the field of mineral resource development, the grade of the original ore is one of the key factors that determine the effectiveness of resource recovery. Low-grade fine-grained tungsten-tin ore has always been a difficult problem for mineral processing. This type of ore not only has a low tungsten-tin content, but also has a fine mineral distribution and complex composition, which makes it difficult for traditional mineral processing technology to accurately separate and efficiently recover, and resource waste is extremely common. This method can achieve a final product of tungsten-tin mixed concentrate with WO3+Sn>24% when the original ore grade is WO30.20%-0.40% and Sn0.10%-0.30%, with a tungsten recovery rate of ≥76% and a tin recovery rate of ≥59%, which is a significant leap compared to traditional processes. This is due to the meticulous control of all aspects of flotation, from the adjustment of slurry concentration, precise addition of reagents, to the efficient collaboration of advanced flotation equipment systems, which fully dissociates and precisely enriches the tungsten and tin minerals in the ore, allowing the precious resources hidden in the fine-grained ore to be "fully utilized", effectively reducing idle resources and loss, and vigorously promoting the sustainable development and utilization of metal resources, which is in line with the industry development vision of efficient resource recycling.

[0040] 2. Significant economic benefits: In the cost control of mineral processing enterprises, equipment and reagent costs are key sectors. In order to adapt to complex working conditions, traditional mineral processing equipment systems have complicated structures and numerous components, requiring large amounts of money to purchase; the installation process is cumbersome, time-consuming, and has high labor costs; due to frequent failures during the operation and maintenance stage, it is necessary to frequently replace parts and hire professional technicians, resulting in high costs. In contrast, the equipment layout adopted in the present invention is simple and sophisticated, and the design is optimized in accordance with the actual needs of ore processing, and redundant structures are removed, so that procurement costs can be effectively reduced; the installation process is simplified, the construction period is greatly shortened, and the labor and time costs are reduced accordingly; the equipment stability is enhanced, the failure rate is significantly reduced, and the maintenance investment drops sharply.

[0041] At the same time, the mineral processing reagent system has been repeatedly studied and adjusted, and the dosage of each reagent is accurately matched to the needs of different flotation stages to eliminate waste caused by excessive use. With the dual benefits of achieving high recovery rates of tungsten and tin and high-grade concentrate output, the company's product quality has been improved, and its market competitiveness has been improved, which can obtain better prices and orders; the steady growth of output has brought economies of scale, accelerated capital recovery, and expanded profit margins, helping companies seize opportunities in market competition and consolidate their development foundations.

[0042] 3. Good environmental benefits: Traditional mineral processing technology has limited resource recovery rate, resulting in a large amount of tungsten and tin metals remaining in the tailings. Long-term storage or improper disposal of these tailings can easily lead to a chain reaction of environmental pollution: heavy metals penetrate into the soil with rainwater, causing soil compaction, nutrient loss, and damage to the soil ecological structure; they flow into surrounding water bodies, causing water turbidity and increased eutrophication, threatening the survival and reproduction of aquatic organisms, and even accumulating through the food chain, posing a potential threat to human health.

[0043] This method, with its excellent resource recovery efficiency, significantly reduces the amount of tungsten and tin metal residues in tailings, reducing pollution risks at the source. The composition of tailings is simplified, and the difficulty and cost of subsequent disposal are reduced simultaneously, which is in line with the development orientation of green mining. This not only demonstrates the environmental protection responsibility of enterprises and helps to establish a good corporate image; it also effectively protects the integrity of the local ecological environment, maintains regional biodiversity, builds a healthy living space for surrounding residents, and achieves harmonious coexistence between enterprises and the ecological environment.

[0044] 4. Strong applicability: Mineral resources are widely distributed around the world. Low-grade fine-grained tungsten-tin ores in different regions are affected by geological causes and have significant differences in characteristics, which requires extremely high universality of mineral processing technology. This method is based on a large amount of practice and technical research and development, accurately understands the common characteristics of such ores and the core points of flotation, and creates a highly universal mineral processing process and process parameters.

[0045] Regardless of the coarse or fine ore particle size, the different mineral distribution forms, or the complex and varied chemical composition, this method can be flexibly adapted and stably output. It provides a mature technical example for the comprehensive recycling of similar low-grade fine tungsten-tin ores. With its outstanding effectiveness, it has quickly gained recognition and reference in the industry, and is of great value for promotion and application.

Brief Description of the Drawings

[0046] Figure 1 It is a schematic diagram of the device of Example 1 of the present invention. [Specific implementation method]

[0047] The present invention will be further described in detail below in conjunction with specific implementations and with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present invention and its application.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] In an embodiment of the present invention, a method for comprehensive utilization of low-grade fine tungsten-tin particles uses an advanced flotation equipment system and mineral processing reagents;

[0050] The advanced flotation equipment system includes a thickener, a desulfurization roughing flotation column, a desulfurization fine flotation column, a tungsten-tin roughing flotation column, a tungsten-tin sweeping flotation column, a tungsten-tin sweeping flotation column, a tungsten-tin fine flotation column, a tungsten-tin fine flotation column and a slurry stirring barrel equipped with each.

[0051] The discharge port of the thickener is connected to the feed port of the desulfurization roughing mixing barrel; the desulfurization roughing mixing barrel is connected to the feed port of the desulfurization roughing flotation column through a pipeline, the concentrate overflow port of the desulfurization roughing flotation column is connected to the desulfurization and selection mixing barrel through a pipeline, and the tailings underflow port of the desulfurization roughing flotation column is connected to the tungsten-tin roughing mixing barrel through a pipeline; the desulfurization and selection mixing barrel is connected to the feed port of the desulfurization and selection flotation column through a pipeline, and the concentrate overflow port of the desulfurization and selection flotation column is transported to the pump pool through a pipeline. The tailings underflow outlet of the concentration flotation column is returned to the desulfurization roughing mixing barrel through a pipeline; the tungsten-tin roughing mixing barrel is connected to the feed inlet of the tungsten-tin roughing flotation column through a pipeline, and the concentrate overflow outlet of the tungsten-tin roughing flotation column is connected to the tungsten-tin concentration-mixing barrel through a pipeline, and the tailings underflow outlet of the tungsten-tin roughing flotation column is connected to the tungsten-tin scavenging-mixing barrel through a pipeline; the tungsten-tin scavenging-mixing barrel is connected to the feed inlet of the tungsten-tin scavenging-flotation column through a pipeline, and the concentrate overflow outlet of the tungsten-tin scavenging-flotation column is connected to the tungsten-tin scavenging-flotation column through a pipeline. The tailings bottom flow outlet of the tungsten-tin scavenging flotation column is connected to the tungsten-tin scavenging second stirring barrel through a pipeline; the tungsten-tin scavenging first stirring barrel is connected to the feed inlet of the tungsten-tin scavenging first flotation column through a pipeline, the concentrate overflow outlet of the tungsten-tin scavenging first flotation column is connected to the tungsten-tin scavenging second stirring barrel through a pipeline, and the tailings bottom flow outlet of the tungsten-tin scavenging first flotation column is returned to the tungsten-tin roughing stirring barrel through a pipeline; the tungsten-tin scavenging second stirring barrel is connected to the feed inlet of the tungsten-tin scavenging second flotation column through a pipeline. The two flotation columns are connected by pipelines, the concentrate overflow port of the second flotation column of tungsten-tin scavenging is connected to the first stirring barrel of tungsten-tin scavenging through the pipeline, and the tailings underflow port of the second flotation column of tungsten-tin scavenging is transported to the thickener through the pipeline for thickening and then to the tailings pump pool; the second stirring barrel of tungsten-tin selection is connected to the feed port of the second flotation column of tungsten-tin selection through the pipeline, the concentrate overflow port of the second flotation column of tungsten-tin selection is transported to the tungsten-tin concentrate pump pool through the pipeline, and the tailings underflow port of the second flotation column of tungsten-tin selection is returned to the first stirring barrel of tungsten-tin selection through the pipeline.

[0052] Each mixing barrel of the desulfurization roughing flotation column, desulfurization fine flotation column, tungsten-tin roughing flotation column, tungsten-tin sweeping flotation column, tungsten-tin sweeping flotation column, tungsten-tin fine flotation column, tungsten-tin fine flotation column is respectively provided with a feeding pump to transport the slurry to the corresponding flotation column feed port.

[0053] The desulfurization roughing flotation column, desulfurization fine flotation column, tungsten-tin roughing flotation column, tungsten-tin sweeping flotation column, tungsten-tin sweeping flotation column, tungsten-tin fine flotation column, tungsten-tin fine flotation column are respectively provided with self-circulating pumps.

[0054] The mineral processing reagents include a regulator, a collector and a frother.

[0055] The above-mentioned mineral processing reagents are added to the slurry in a certain amount at each stage of tungsten-tin desulfurization and mixed flotation. The types and amounts of mineral processing reagents added at each stage are as follows:

[0056] Desulfurization stage:

[0057] Copper sulfate is used as an adjusting agent for activation, and its dosage is 50-150g / t;

[0058] Use 2# oil as foaming agent for foaming, and its dosage is 2-30g / t;

[0059] Butyl xanthate is used as a collector for sulfide ore collection, and its dosage is 30-200g / t.

[0060] Mixed flotation stage:

[0061] Sodium carbonate is used as an adjusting agent to soften water and adjust the pH of the slurry, with a dosage of 300-900g / t;

[0062] Lead nitrate is used as a regulator to activate tungsten and tin, with a dosage of 150g-450g / t;

[0063] Acidified water glass is used as a regulator to suppress iron impurities and silicates, with a dosage of 30-300g / t;

[0064] GY-1 with excellent tungsten-tin capture and selectivity is used as a tungsten-tin collector to capture tungsten-tin, and its dosage is 10-200g / t. GY-2 is used as an auxiliary tungsten-tin collector, and its dosage is 1-10g / t.

[0065] A method for comprehensive utilization of low-grade fine tungsten-tin particles comprises the following steps:

[0066] Step (1): Concentration: The low-grade fine-grained tungsten-tin ore slurry is concentrated by a thickener;

[0067] Step (2): Desulfurization: After concentration, the low-grade fine-grained tungsten-tin slurry is desulfurized by a desulfurization flotation column; the underflow slurry of the thickener 1 is mixed with a regulator, a collector, and a frother by a desulfurization roughing mixing barrel, and the slurry after the addition of the regulator is fed into the desulfurization roughing flotation column by a feed pump, the concentrate of the desulfurization roughing flotation column flows into the desulfurization concentration flotation column, and the tailings of the desulfurization roughing flotation column are fed into a tungsten-tin roughing mixing barrel, and the regulator and collector are added to mix the slurry, and then fed into the tungsten-tin roughing flotation column by a feed pump;

[0068] Step (3): Mixed flotation: After desulfurization, the low-grade fine tungsten-tin ore pulp is subjected to tin-tungsten mixed flotation through each operating flotation column; the concentrate of the tungsten-tin roughing flotation column flows into the tungsten-tin selection first stirring barrel, and the adjusting agent is added to adjust the slurry, and then fed into the tungsten-tin selection first flotation column through the feeding pump; the tailings of the tungsten selection roughing flotation column are fed into the tungsten-tin scavenging selection first stirring barrel, and the adjusting agent and collector are added to adjust the slurry, and then fed into the tungsten-tin scavenging selection first flotation column through the feeding pump; the concentrate of the tungsten-tin selection first flotation column flows into the tungsten-tin selection second stirring barrel, and the collector is added to adjust the slurry, and then fed into the tungsten-tin selection second flotation column through the feeding pump, and the tailings of the tungsten-tin selection first flotation column are returned to the tungsten-tin selection second flotation column. The roughing mixing barrel realizes closed-loop circulation; the concentrate of the tungsten-tin scavenging flotation column No. 1 is returned to the tungsten-tin roughing mixing barrel, and the tailings of the tungsten-tin scavenging flotation column No. 1 is fed into the tungsten-tin scavenging mixing barrel No. 2 to add the collector to adjust the slurry, and then fed into the tungsten-tin scavenging flotation column No. 2 through the feed pump; the concentrate of the tungsten-tin scavenging flotation column No. 2 is returned to the tungsten-tin scavenging mixing barrel No. 1, and the tailings of the tungsten-tin scavenging flotation column No. 2 enters the thickener and flows into the tailings pump pool and is pumped away; the concentrate of the tungsten-tin concentration flotation column No. 2 flows into the tungsten-tin concentrate pump pool and is pumped away, and the tailings of the tungsten-tin concentration flotation column No. 2 returns to the tungsten-tin concentration mixing barrel No. 1, realizing closed-loop circulation and producing tungsten-tin mixed concentrate.

[0069] In order to make the disclosure of the present invention more complete, it is described below through more specific embodiments.

[0070] Example 1

[0071] Step 1: The low-grade fine-grained tungsten-tin slurry is concentrated by a thickener 1. The slurry concentration is 30%, the tungsten-tin grade is WO30.20%-0.40%, Sn0.10%-0.30%, and the particle size is mainly concentrated at -0.025mm.

[0072] Step 2: After concentration, the low-grade fine-grained tungsten-tin slurry is desulfurized by the desulfurization flotation column 4. The thickener underflow slurry passes through the desulfurization roughing mixing barrel 2, and 100g / t of copper sulfate, 150g / t of butyl xanthate, and 20g / t of 2# oil are added to adjust the slurry. The slurry adjusted by adding drugs is fed into the desulfurization roughing flotation column 4 by the feed pump, and the concentrate of the desulfurization roughing flotation column 4 flows into the desulfurization concentration flotation column 3. The tailings of the desulfurization roughing flotation column 4 are fed into the tungsten-tin roughing mixing barrel 12, and 600g / t of sodium carbonate, 300g / t of lead nitrate, 120g / t of GY-1, and 6g / t of GY-2 are added to adjust the slurry, and then fed into the tungsten-tin roughing flotation column 5 by the feed pump.

[0073] Step 3: After desulfurization, the low-grade fine-grained tungsten-tin ore pulp is mixed and floated through each operating flotation column. The concentrate of the tungsten-tin roughing flotation column 5 flows into the tungsten-tin selection mixing barrel 14, and GY-1 is added at a dosage of 20g / t for slurry adjustment, and is fed into the tungsten-tin selection flotation column 7 through a feed pump. The tailings of the tungsten-tin selection roughing flotation column 5 are fed into the tungsten-tin scavenging selection mixing barrel 13, and GY-1 is added at a dosage of 60g / t and acidified water glass is added at a dosage of 300g / t for slurry adjustment, and is fed into the tungsten-tin scavenging selection flotation column 6 through a feed pump; the concentrate of the tungsten-tin selection flotation column 7 flows into the tungsten-tin selection second mixing barrel 16, and GY-1 is added at a dosage of 10g / t and acidified water glass is added at a dosage of 120g / t for slurry adjustment, and is fed into the tungsten-tin selection second flotation column 9 through a feed pump. The tailings of the tungsten-tin selection flotation column 7 are returned to the tungsten-tin selection second flotation column 7. To the tungsten-tin roughing stirring barrel 12, to achieve closed-loop circulation; the concentrate of the tungsten-tin scavenging flotation column 6 returns to the tungsten-tin roughing stirring barrel 12, the tailings of the tungsten-tin scavenging flotation column 6 are fed into the tungsten-tin scavenging second stirring barrel 15, GY-1 is added at a dosage of 30g / t for slurry adjustment, and fed into the tungsten-tin scavenging second flotation column 8 through the feed pump; the concentrate of the tungsten-tin scavenging second flotation column 8 returns to the tungsten-tin scavenging first stirring barrel 13, the tailings of the tungsten-tin scavenging second flotation column 8 flow into the tailings pump pool and pump away; the concentrate of the tungsten-tin concentrating second flotation column 9 flows into the tungsten-tin concentrate pump pool and pumps away, the tailings of the tungsten-tin concentrating second flotation column 9 return to the tungsten-tin concentrating first stirring barrel 14, to achieve closed-loop circulation, and produce tungsten-tin mixed concentrate. Schematic diagram of each device is shown in Figure 1 .

[0074] Example 2

[0075] Step (1) in Example 1 is adjusted so that the concentration of the low-grade tungsten-tin ore pulp after being concentrated by the thickener 1 is 50%. The remaining steps remain unchanged to produce a tungsten-tin mixed concentrate.

[0076] Example 3

[0077] Step (2) in Example 1 was adjusted to add 120 g / t of copper sulfate, 160 g / t of butyl xanthate, and 30 g / t of 2# oil to the desulfurization roughing stirring barrel 2 for slurry preparation. The remaining steps remained unchanged to produce a tungsten-tin mixed concentrate.

[0078] Example 4

[0079] Step (2) in Example 1 is adjusted to add 600 g / t of sodium carbonate, 300 g / t of lead nitrate, 150 g / t of GY-1 and 6 g / t of GY-2 to the tungsten-tin roughing mixing barrel 12 for slurry preparation. The remaining steps remain unchanged to produce a tungsten-tin mixed concentrate.

[0080] Example 5

[0081] Step (3) in Example 1 is adjusted to add 10 g / t of GY-1 to the first stirring barrel 14 of tungsten tin selection for slurry mixing; add 60 g / t of GY-1 to the first stirring barrel 13 of tungsten tin scavenging selection for slurry mixing; add 5 g / t of GY-1 to the second stirring barrel 16 of tungsten tin selection for slurry mixing; add 20 g / t of GY-1 to the second stirring barrel 15 of tungsten tin scavenging selection for slurry mixing. The remaining steps remain unchanged to produce a tungsten-tin mixed concentrate.

[0082] The tungsten-tin mixed concentrate products produced in Examples 1-5 were analyzed and the grades of the tungsten-tin mixed concentrate products and the tungsten-tin recovery rates were as shown in Table 1:

[0083] Table 1: Grade of tungsten-tin mixed concentrate and tungsten-tin recovery rate of products in Examples 1-5

[0084] Example Grade of tungsten-tin mixed concentrate, % Tungsten recovery rate, % Recovery rate of tin, % Example 1 >24.8 76.5 60.6 Example 2 >26.3 76.1 59.2 Example 3 >24.5 76.8 60.3 Example 4 >25.2 76.2 59.4 Example 5 >24.1 77.3 61.2

[0085] By analyzing the results of Examples 1-5, we can clearly and accurately grasp the actual effect of the desulfurization-tin-tungsten mixed flotation process designed for low-grade fine-grained tungsten-tin ore, as well as the application advantages of the new flotation equipment system and mineral processing agents.

[0086] The grade of the original ore is between WO30.20%-0.40% and Sn0.10%-0.30%, which belongs to the category of typical low-grade ore. The beneficiation of this type of ore is difficult, and it is difficult to achieve the ideal enrichment effect with conventional processes in the past. However, this process performs well. The tungsten-tin mixed concentrates produced by each embodiment have reached the level of WO3+Sn>24%. Among them, after the pulp concentration is adjusted to 50% in Example 2, the concentrate grade is increased to>26.3%, highlighting the key role of pulp concentration in the beneficiation process. Appropriate pulp concentration is conducive to the uniform dispersion of flotation reagents, so that they can fully contact and react with the ore particles, allowing more tungsten-tin minerals to be effectively dissociated and enriched, thereby improving the concentrate grade. Although the dosage and preparation of the other embodiments have changed, the concentrate grade is still stably maintained at a high level, which fully verifies the reliability of this process in controlling the quality of the concentrate.

[0087] Comparing the tungsten recovery rates of Examples 1-5, the experimental data strongly proves the efficient recovery ability of the process. In Example 1, the tungsten recovery rate reached 76.5%, laying the foundation, indicating that the basic process parameter settings are reasonable and effective, and can better capture the tungsten element in the ore. Example 5 focuses on adjusting the amount of GY-1 in each stirring barrel in the mixed flotation stage, thereby increasing the tungsten recovery rate to 77.3%, highlighting the importance of precise formulation of mineral processing agents. As a key collector, GY-1 is used in an amount that adapts to the characteristics of tungsten-tin minerals in different flotation stages, and is accurately and efficiently combined with the mineral surface to reduce tungsten residues in the tailings and enhance the collection effect. The tungsten recovery rates of the remaining examples are stably maintained at ≥76%, demonstrating the robustness and efficiency of the process.

[0088] Looking at the recovery rate of tin, we also achieved ideal results. The recovery rate of tin in Example 1 was 60.6%. When the process parameters were adjusted in subsequent examples, the recovery rate of tin remained stable at ≥59%. Like Example 3, the dosage of the desulfurization roughing stirring barrel reagent was adjusted, and Example 4 fine-tuned the combination of tungsten and tin roughing stirring barrel reagents. The recovery effect of tin did not decrease significantly, indicating that this process is suitable for the recovery of tin elements. The various reagents work together in different flotation links, which can not only separate sulfide ores, but also suppress impurities, creating a good environment for the floating and enrichment of tin and ensuring efficient recovery.

[0089] In general, these five groups of examples fully verify the scientificity and advancement of this process. The new flotation equipment has a reasonable system layout, efficient stirring and conveying, and practical self-circulation function, providing hardware support for slurry processing and mineral sorting; the mineral processing reagents are prepared on demand and work closely with the equipment. The two work together to overcome the difficulty of beneficiation of low-grade fine-grained tungsten-tin ore, providing a feasible example for the selection of similar ores, which is of great promotion value and conducive to promoting efficient resource recovery and sustainable development in the industry.

[0090] Those skilled in the art will recognize that numerous variations to the above description are possible, and that the examples are intended only to describe one or more specific implementations.

[0091] Although what is considered as exemplary embodiments of the present invention has been described and described, it will be understood by those skilled in the art that various changes and substitutions may be made thereto without departing from the spirit of the present invention. In addition, many modifications may be made to adapt specific situations to the teachings of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but the present invention may also include all embodiments and their equivalents that fall within the scope of the present invention.

Claims

1. A method for comprehensive utilization of low-grade fine tungsten-tin particles, characterized in that: Use advanced flotation equipment systems and mineral processing reagents; The advanced flotation equipment system includes a thickener, a desulfurization roughing flotation column, a desulfurization fine flotation column, a tungsten-tin roughing flotation column, a tungsten-tin sweeping flotation column, a tungsten-tin sweeping flotation column, a tungsten-tin fine flotation column, a tungsten-tin fine flotation column and a slurry stirring barrel equipped with each; The mineral processing reagents include a regulator, a collector and a frother.

2. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 1 is characterized in that: In the advanced flotation equipment system, the thickener outlet is connected to the feed inlet of the desulfurization roughing mixing barrel; the desulfurization roughing mixing barrel is connected to the feed inlet of the desulfurization roughing flotation column through a pipeline, the concentrate overflow of the desulfurization roughing flotation column is connected to the desulfurization concentration mixing barrel through a pipeline, and the tailings underflow outlet of the desulfurization roughing flotation column is connected to the tungsten-tin roughing mixing barrel through a pipeline; the desulfurization concentration mixing barrel is connected to the feed inlet of the desulfurization concentration flotation column through a pipeline, and the concentrate overflow of the desulfurization concentration flotation column is connected to the desulfurization concentration flotation column through a pipeline. The tailings underflow outlet of the desulfurization and concentration flotation column is returned to the desulfurization roughing mixing barrel through a pipeline; the tungsten-tin roughing mixing barrel is connected to the feed inlet of the tungsten-tin roughing flotation column through a pipeline, the concentrate overflow outlet of the tungsten-tin roughing flotation column is connected to the tungsten-tin concentration-mixing barrel through a pipeline, and the tailings underflow outlet of the tungsten-tin roughing flotation column is connected to the tungsten-tin scavenging-mixing barrel through a pipeline; the tungsten-tin scavenging-mixing barrel is connected to the feed inlet of the tungsten-tin scavenging-flotation column through a pipeline, and the tungsten-tin scavenging-flotation column is connected to the tungsten-tin scavenging-flotation column. The overflow port of concentrate is connected to the tungsten-tin roughing mixing barrel through a pipeline, and the tailings underflow port of the tungsten-tin scavenging flotation column is connected to the tungsten-tin scavenging mixing barrel through a pipeline; the tungsten-tin selection mixing barrel is connected to the feed port of the tungsten-tin selection flotation column through a pipeline, and the overflow port of the tungsten-tin selection flotation column is connected to the tungsten-tin selection mixing barrel through a pipeline, and the tailings underflow port of the tungsten-tin selection flotation column is returned to the tungsten-tin roughing mixing barrel through a pipeline; the tungsten-tin scavenging mixing barrel and the feed port of the tungsten-tin scavenging flotation column are connected to the tungsten-tin selection mixing barrel through a pipeline. The outlets are connected by pipelines, the concentrate overflow outlet of the second tungsten-tin scavenging flotation column is connected to the first tungsten-tin scavenging stirring barrel through a pipeline, and the tailings underflow outlet of the second tungsten-tin scavenging flotation column is transported to the thickener through a pipeline and then to the tailings pump pool for thickening; the second tungsten-tin selection stirring barrel is connected to the feed inlet of the second tungsten-tin selection flotation column through a pipeline, the concentrate overflow outlet of the second tungsten-tin selection flotation column is transported to the tungsten-tin concentrate pump pool through a pipeline, and the tailings underflow outlet of the second tungsten-tin selection flotation column is returned to the first tungsten-tin selection stirring barrel through a pipeline.

3. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 1 is characterized in that: Each mixing barrel of the desulfurization roughing flotation column, desulfurization fine flotation column, tungsten-tin roughing flotation column, tungsten-tin sweeping flotation column, tungsten-tin sweeping flotation column, tungsten-tin fine flotation column, tungsten-tin fine flotation column is respectively provided with a feeding pump to transport the slurry to the corresponding flotation column feed port.

4. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 1 is characterized in that: The desulfurization roughing flotation column, desulfurization fine flotation column, tungsten-tin roughing flotation column, tungsten-tin sweeping flotation column, tungsten-tin sweeping flotation column, tungsten-tin fine flotation column, tungsten-tin fine flotation column are respectively provided with self-circulating pumps.

5. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 1 is characterized in that: The above-mentioned mineral processing reagents are added to the ore pulp in certain amounts at each stage of tungsten-tin desulfurization and tin-tungsten mixed flotation. The types and amounts of mineral processing reagents added in the desulfurization stage are as follows: Copper sulfate is used as an adjusting agent for activation, and its dosage is 50-150g / t; Use 2# oil as foaming agent for foaming, and its dosage is 2-30g / t; Butyl xanthate is used as a collector for sulfide ore collection, and its dosage is 30-200g / t.

6. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 1 is characterized in that: The above-mentioned mineral processing reagents are added to the ore pulp in certain amounts at each stage of tungsten-tin desulfurization and tin-tungsten mixed flotation. The types and amounts of mineral processing reagents added in the mixed flotation stage are as follows: Sodium carbonate is used as an adjusting agent to soften water and adjust the pH of the slurry, with a dosage of 300-900g / t; Lead nitrate is used as a regulator to activate tungsten and tin, with a dosage of 150g-450g / t; Acidified water glass is used as a regulator to suppress iron impurities and silicates, with a dosage of 30-300g / t; GY-1 with excellent tungsten-tin capture and selectivity is used as a tungsten-tin collector to capture tungsten-tin, and its dosage is 10-200g / t. GY-2 is used as an auxiliary tungsten-tin collector, and its dosage is 1-10g / t.

7. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 1 is characterized in that: The following steps are involved: Step (1): Concentration: The low-grade fine-grained tungsten-tin ore slurry is concentrated by a thickener; Step (2): Desulfurization: After concentration, the low-grade fine-grained tungsten-tin slurry is desulfurized by a desulfurization flotation column; the underflow slurry of the thickener 1 is mixed with a regulator, a collector, and a frother by a desulfurization roughing mixing barrel, and the slurry after the addition of the regulator is fed into the desulfurization roughing flotation column by a feed pump, the concentrate of the desulfurization roughing flotation column flows into the desulfurization concentration flotation column, and the tailings of the desulfurization roughing flotation column are fed into a tungsten-tin roughing mixing barrel, and the regulator and collector are added to mix the slurry, and then fed into the tungsten-tin roughing flotation column by a feed pump; Step (3): Mixed flotation: After desulfurization, the low-grade fine tungsten-tin ore pulp is subjected to tin-tungsten mixed flotation through each operating flotation column; the concentrate of the tungsten-tin roughing flotation column flows into the tungsten-tin selection first stirring barrel, and the adjusting agent is added to adjust the slurry, and then fed into the tungsten-tin selection first flotation column through the feeding pump; the tailings of the tungsten selection roughing flotation column are fed into the tungsten-tin scavenging selection first stirring barrel, and the adjusting agent and collector are added to adjust the slurry, and then fed into the tungsten-tin scavenging selection first flotation column through the feeding pump; the concentrate of the tungsten-tin selection first flotation column flows into the tungsten-tin selection second stirring barrel, and the collector is added to adjust the slurry, and then fed into the tungsten-tin selection second flotation column through the feeding pump, and the tailings of the tungsten-tin selection first flotation column are returned to the tungsten-tin selection second flotation column. The roughing mixing barrel realizes closed-loop circulation; the concentrate of the tungsten-tin scavenging flotation column No. 1 is returned to the tungsten-tin roughing mixing barrel, and the tailings of the tungsten-tin scavenging flotation column No. 1 is fed into the tungsten-tin scavenging mixing barrel No. 2 to add the collector to adjust the slurry, and then fed into the tungsten-tin scavenging flotation column No. 2 through the feed pump; the concentrate of the tungsten-tin scavenging flotation column No. 2 is returned to the tungsten-tin scavenging mixing barrel No. 1, and the tailings of the tungsten-tin scavenging flotation column No. 2 enters the thickener and flows into the tailings pump pool and is pumped away; the concentrate of the tungsten-tin concentration flotation column No. 2 flows into the tungsten-tin concentrate pump pool and is pumped away, and the tailings of the tungsten-tin concentration flotation column No. 2 returns to the tungsten-tin concentration mixing barrel No. 1, realizing closed-loop circulation and producing tungsten-tin mixed concentrate.

8. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 7 is characterized in that: In step (1), the concentration of the concentrated slurry is controlled to be between 30% and 50%.

9. The method for comprehensive utilization of low-grade fine tungsten-tin particles according to claim 7 is characterized in that: Step (1) controls the tungsten-tin grade of the concentrated slurry to be WO30.20%-0.40%, Sn0.10%-0.30%, and the particle size range is concentrated in the range of 0.005-0.15 mm.

10. A tungsten-tin mixed concentrate prepared according to the method according to any one of claims 1 to 9.

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