Method for leaching and separating valuable metals at normal temperature and pressure by wet-ground activated hydrochloric acid

Abstract

The invention relates to a method for leaching and separating valuable metals at normal temperature and pressure by wet-ground activated hydrochloric acid, and belongs to the field of vanadium-titanium-iron concentrate treatment. The method comprises the following steps: S1, preparing a vanadium titano-magnetite concentrate sample; s2, the sample is subjected to wet grinding activation, and an ore grinding auxiliary is added; s3, a hydrochloric acid solution is adopted as a leaching agent, the sample obtained after wet grinding is mixed with the hydrochloric acid solution, and stirring leaching is conducted at the normal temperature and the normal pressure; and S4, after leaching is finished, solid-liquid separation is carried out to obtain leaching residues and leaching liquid, and the leaching rate is calculated. According to the method, the ore grinding aid is added under the normal-temperature and normal-pressure conditions to assist hydrochloric acid in selective leaching and separate iron, vanadium and titanium, so that the production cost is reduced, the environmental pollution is reduced, and meanwhile, the leaching rate is increased. The problem that iron, titanium and vanadium cannot be directly leached and separated from vanadium titano-magnetite iron concentrate hydrochloric acid at normal temperature and normal pressure in the prior art is solved.

Description

Technical Field

[0001] The invention relates to a method for separating valuable metals by wet grinding activated hydrochloric acid leaching at normal temperature and pressure, and belongs to the field of vanadium-titanium-iron concentrate processing. Background Art

[0002] The vanadium-titanium magnetite in the Panxi region is famous for its complex mineral phase and special mineral structure. After the mining and selection process, it can produce magnetite concentrate containing vanadium and titanium, namely vanadium-titanium magnetite concentrate. This concentrate is an important primary product of valuable metals such as iron, vanadium, and titanium, and recovers about 50% of the titanium resources in the original ore. Vanadium-titanium magnetite concentrate is considered to be one of the most difficult minerals to be comprehensively utilized in the world. The primary task of its comprehensive utilization is to achieve the effective separation of iron, titanium, vanadium and other components, and the second is to ensure the rational and economic utilization of these components.

[0003] The main mineral component of Panxi iron ore concentrate is titanomagnetite, which has an iron (TFe) grade of about 54%. It also contains a lot of impurities such as sulfur, aluminum and magnesium. These impurities lead to high costs for subsequent blast furnace smelting and may cause environmental problems. Panzhihua iron ore concentrate is mainly composed of titanomagnetite, ilmenite, ilmenite (TiO 2 The content is about 11.5%), sulfides (mainly pyrrhotite and pyrite) and total gangue (mainly pyroxene, labradorite, olivine), etc. The existing mineral processing technology can no longer fully and effectively recover the iron resources in the ore, especially for those vanadium-titanium magnetite ores with fine particle size.

[0004] The Panxi region has rich vanadium-titanium iron concentrate resources, but due to its complex composition and special mineral structure, the traditional blast furnace method faces many challenges in the comprehensive utilization of these resources. Therefore, non-blast furnace methods have gradually become the focus of research. Many scholars have conducted in-depth research on the direct reduction method. This method uses a reducing agent to directly reduce iron oxides to metallic iron to achieve the separation of iron from vanadium and titanium. Among them, gas-based direct reduction technology has attracted much attention due to its high reduction efficiency and environmental friendliness. However, it has strict requirements for the control of reducing atmosphere and temperature. In addition, molten salt electrolysis also shows certain potential. In a high-temperature molten salt system, iron ions are reduced and precipitated at the cathode through electrolysis, thereby achieving the purpose of separation and extraction. However, this method has problems such as high energy consumption and complex electrolysis equipment. Microwave heating, as an emerging technology, has also been studied in the treatment of Panxi vanadium-titanium iron concentrate. Microwaves can quickly heat materials and promote reactions, but their economy and feasibility still need to be further explored in large-scale applications. Other researchers have tried bioleaching, which uses the metabolism of specific microorganisms to leach valuable metals. Although this method has the advantage of being environmentally friendly, the leaching cycle is long and the growth conditions of microorganisms are relatively harsh.

[0005] Due to its unique mineral properties, acid leaching of Panxi vanadium-titanium iron concentrate has become an important research direction for extracting valuable elements. In recent years, research on acid leaching of Panxi vanadium-titanium iron concentrate has made significant progress. However, these research results still have some problems, such as large acid consumption, the need to combine with roasting or smelting process, the need to leaching under heating and pressure conditions, serious equipment corrosion, and complex subsequent treatment of leachate, and there are huge safety and environmental risks in production under high temperature and high pressure conditions. The research on the separation effect and existing problems of hydrochloric acid leaching of vanadium-titanium magnetite concentrate at room temperature and pressure is still blank. The leaching process at room temperature and pressure has certain environmental advantages in terms of energy consumption, equipment maintenance, safety and pollution control, and has good research value from the perspective of social benefits and economic costs. The reason for the blank in the research on the direct leaching process of hydrochloric acid at room temperature and pressure for vanadium-titanium magnetite concentrate is that the corrosion rate of hydrochloric acid on iron concentrate is very slow at room temperature and pressure. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the existing technology cannot effectively realize the direct leaching of iron, vanadium and titanium by hydrochloric acid at room temperature and pressure to vanadium-titanium magnetite iron concentrate.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure, comprising the following steps:

[0008] S1. Prepare vanadium-titanium-iron concentrate sample;

[0009] S2, wet grinding and activating the sample, and adding grinding aids;

[0010] S3, using hydrochloric acid solution as a leaching agent, mixing the wet-milled sample with the hydrochloric acid solution, and stirring and leaching at normal temperature and pressure;

[0011] S4. After the leaching is completed, the solid and liquid are separated to obtain the leaching residue and the leaching liquid, and the leaching rate is calculated.

[0012] Wherein, the grinding concentration of the vanadium-titanium magnetite concentrate sample in step S1 of the above method is 60%±7%.

[0013] Wherein, in step S2 of the above method, grinding balls with a diameter of 10 mm to 25 mm are used for wet grinding, the ball-to-material ratio is 20:1, and the wet grinding time is 1 h to 2 h.

[0014] Wherein, the grinding aid added in step S2 of the above method is ferric chloride, and the amount of ferric chloride added is 0.5% to 0.9% of the mass of the iron concentrate.

[0015] Wherein, in step S3 of the above method, the initial concentration of the hydrochloric acid solution is 20% to 35%, and deionized water is added for dilution according to the leaching liquid-solid ratio (6 to 10):1.

[0016] Furthermore, in step S3 of the above method, the initial concentration of hydrochloric acid is 25.5%, the leaching liquid-solid ratio is 8:1, the leaching time is 2h to 4h, and the leaching stirring speed rate is 200r / min to 600r / min.

[0017] Wherein, in step S3 of the above method, a leaching aid needs to be added, and the leaching aid is ammonium fluoride.

[0018] Furthermore, in the above method, the amount of ammonium fluoride added is 1% to 7% of the mass of the leached material.

[0019] Wherein, in step S3 of the above method, the leaching temperature is maintained at room temperature 25°C±2°C, under one atmosphere of pressure, and the leaching time is 2h to 4h.

[0020] Furthermore, in step S3 of the above method, the stirring speed is set to 500 r / min to 600 r / min at the initial stage of leaching, and gradually decreases to 200 r / min to 250 r / min as the leaching reaction proceeds.

[0021] The beneficial effects of the present invention are:

[0022] (1) This method achieves hydrochloric acid leaching at room temperature and pressure by optimizing the wet grinding activation process, avoiding the safety hazards of high temperature and high pressure production. The specific grinding equipment, media and grinding aids are used to significantly improve the reaction activity of iron ore concentrate, creating favorable conditions for subsequent hydrochloric acid leaching. The leaching rate of valuable elements is increased by 20% to 30% compared with the traditional process.

[0023] (2) The method rationally designs the hydrochloric acid leaching process parameters, including leaching agent formula, leaching temperature, stirring speed and leaching time, thereby reducing the consumption of leaching agent and energy while ensuring the leaching rate, and reducing the production cost by about 17%.

[0024] (3) The method produces little waste residue during the entire process. The residue after leaching is mainly TiO with a grade of about 38%. 2 , can be enriched to more than 45% through ore dressing, and further processed into titanium-rich materials by pyrometallurgy. The waste slag has low harmful substance content, which is easy to carry out subsequent harmless treatment and comprehensive utilization, reducing pollution to the environment, and conforming to the concept of green chemistry and sustainable development. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with embodiments.

[0026] The method of wet grinding activated hydrochloric acid leaching and separation of valuable metals at room temperature and pressure of the present invention comprises the following steps:

[0027] S1. Prepare vanadium-titanium-iron concentrate sample;

[0028] S2, wet grinding and activating the sample, and adding grinding aids;

[0029] S3, using hydrochloric acid solution as a leaching agent, mixing the wet-milled sample with the hydrochloric acid solution, and stirring and leaching at normal temperature and pressure;

[0030] S4, after the leaching is completed, the solid and liquid are separated to obtain the leaching residue and the leaching liquid, and the leaching rate is calculated. It can be understood by those skilled in the art that the present invention proposes a new leaching aid that can increase the reaction rate of hydrochloric acid and iron ore concentrate at room temperature and pressure.

[0031] Preferably, the grinding concentration of the vanadium-titanium magnetite concentrate sample in step S1 of the above method is 60% ± 7%. It can be understood by those skilled in the art that the purpose of this method is mainly to mechanically activate the vanadium-titanium magnetite concentrate by grinding steel balls, so that the material can be leached with hydrochloric acid at normal temperature and pressure. The higher the grinding concentration, the denser the contact between the steel balls and the vanadium-titanium magnetite iron concentrate, which better promotes the mechanical activation effect of the steel balls on the vanadium-titanium magnetite iron concentrate. However, if the grinding concentration exceeds 70%, the steel balls lose fluidity in the ball mill and cannot be ground, so the actual preferred grinding concentration of the vanadium-titanium magnetite concentrate sample is 60% ± 7%.

[0032] Preferably, in step S2 of the above method, grinding balls of Φ10 mm to 25 mm are used for wet grinding, the ball-to-material ratio is 20:1, and the wet grinding time is 1 h to 2 h. It can be understood by those skilled in the art that the grinding balls used in this method are relatively small, and the ball-to-material ratio is usually in the range of 1:1 to 5:1, and the ball-to-material ratio used in this method is also relatively high. Small grinding balls and high ball-to-material ratios are both for better mechanical activation of vanadium-titanium magnetite iron concentrate during grinding. If, on the contrary, the grinding balls are large and the ball-to-material ratio is small, the iron concentrate will be quickly crushed by the steel balls until it becomes muddy during grinding, and the purpose of mechanical activation of the vanadium-titanium magnetite iron concentrate by the steel balls cannot be achieved.

[0033] Preferably, the grinding aid added in step S2 of the above method is ferric chloride, and the amount of ferric chloride added is 0.5% to 0.9% of the mass of the iron concentrate. It can be understood by those skilled in the art that the grinding aid can change the physical and chemical properties of the mineral surface, promote lattice distortion and chemical bond breaking, and effectively improve the leaching rate of valuable elements. Add an additive in the grinding process before leaching, the main component of which is ferric chloride, and the amount added is 0.5 to 0.9% of the mass of the iron concentrate. This composite activator can be adsorbed on the surface of the mineral, change the physical and chemical properties of the mineral surface, promote lattice distortion and chemical bond breaking, thereby effectively improving the leaching rate of valuable elements. Improve the leaching rate: Ferric chloride can increase the leaching rate of certain metals in the hydrochloric acid system, which is mainly due to its own oxidizing ability and increased chloride ion concentration. In some cases, the addition of ferric chloride can promote the leaching of metals such as copper, silver and bismuth. Formation of complex: Fe 3+ and Cl - The complex formed [FeCl 4 ] - Compared with free Fe 3+ It is easier to be extracted, so the amount of hydrochloric acid added is positively correlated with the extraction efficiency. Promote oxidation reaction: Ferric chloride has strong oxidizing properties and can react with hydrochloric acid to generate strong oxidants such as chlorine. These strong oxidants can further oxidize the ferrous ions (Fe 2+ ) to iron ions (Fe 3+ ), thereby increasing the leaching rate of iron. Influence on pH value: When ferric chloride dissolves in water, it will form an acidic environment, which may affect the pH value of hydrochloric acid leaching, and then affect the leaching efficiency and selectivity. Reduce side reactions: In some cases, ferric chloride can reduce side reactions in the hydrochloric acid leaching process, such as reducing the hydrolysis or precipitation of metal ions, thereby increasing the leaching rate of the target metal. Promote flocculation: Ferric chloride has a flocculation effect in aqueous solution and can promote the coagulation of suspended particles, which may have a positive effect on the clarification of the leachate and subsequent separation and purification processes. Environmental protection and cost-effectiveness: The use of ferric chloride can improve leaching efficiency, reduce the consumption of chemical reagents, and reduce production costs. And due to its good effect and low price, it has relatively little impact on the environment.

[0034] As a fluorine-containing leaching agent, ammonium fluoride can be used together with hydrochloric acid and other acids to significantly increase the leaching rate of iron in iron ore or steel slag. Ammonium fluoride forms compounds with silicon and aluminum in the waste slag, preventing the formation of colloidal silica and fine solid particles, thus facilitating the positive reaction between the waste slag and the mixed acid. In addition, ammonium fluoride can convert Fe 3+ and Fe 2+ Desorption from silicate into liquid further increases the leaching rate of iron ore or steel slag. This desorption helps to increase the recovery rate of iron metal.

[0035] In summary, ferric chloride not only plays a role in promoting grinding and mechanically activating vanadium-titanium magnetite iron concentrate in grinding, but also plays multiple roles in promoting metal leaching, improving leaching efficiency and selectivity, and reducing side reactions together with ammonium fluoride in the hydrochloric acid leaching process. Therefore, the combined action of ferric chloride and ammonium fluoride promotes the hydrochloric acid leaching of vanadium-titanium magnetite iron concentrate at room temperature and pressure after mechanical activation.

[0036] Preferably, in the step S3 of the above method, the initial concentration of the hydrochloric acid solution is 20% to 35%, and deionized water is added for dilution according to the ratio of the leaching liquid to solid (6 to 10): 1. It can be understood by those skilled in the art that, in order to ensure the leaching rate, the method explores the optimal range of the initial concentration of the hydrochloric acid solution of 20% to 35%, and deionized water is added for dilution according to the ratio of the leaching liquid to solid (6 to 10): 1, taking into account both the production cost and the test data.

[0037] Further, in the step S3 of the above method, the initial concentration of hydrochloric acid is 25.5%, the leaching liquid-solid ratio is 8:1, the leaching time is 2h to 4h, and the leaching stirring speed rate is 200r / min to 600r / min. It can be understood by those skilled in the art that in order to ensure the leaching rate, the method further preferably has an initial concentration of hydrochloric acid of 25.5%, a leaching liquid-solid ratio of 8:1, a leaching time of 2h to 4h, and a leaching stirring speed rate of 200r / min to 600r / min.

[0038] Preferably, a leaching aid is added in step S3 of the above method, and the leaching aid is ammonium fluoride. It can be understood by those skilled in the art that the leaching aid ammonium fluoride reacts with certain insoluble minerals in the iron ore concentrate to further improve the leaching effect. Therefore, the preferred leaching aid in this method is ammonium fluoride.

[0039] Preferably, the amount of ammonium fluoride added in the above method is 1% to 7% of the mass of the leached material. It can be understood by those skilled in the art that, in order to ensure the leaching rate, the method takes into account both production costs and test data in the experiment, and the optimal range explored is that the amount of ammonium fluoride added is 1% to 7% of the mass of the leached material.

[0040] Preferably, the leaching temperature in step S3 of the above method is maintained at room temperature 25°C ± 2°C, under one atmosphere, and the leaching time is 2h to 4h. It can be understood by those skilled in the art that

[0041] Preferably, the stirring speed in step S3 of the above method is set to 500r / min~600r / min at the initial stage of leaching, and gradually decreases to 200r / min~250r / min as the leaching reaction proceeds. It can be understood by those skilled in the art that the leaching condition control can flexibly adjust the stirring speed according to the progress of the leaching reaction to adapt to the reaction requirements at different stages. Therefore, the preferred stirring speed of this method is set to 500r / min~600r / min at the initial stage of leaching, and gradually decreases to 200r / min~250r / min as the leaching reaction proceeds.

[0042] Comparative Example 1: Wet leaching without additives

[0043] 1. Sample preparation: The sample comes from the iron concentrate produced by a ore dressing plant in Panzhihua. The particle size is -0.074 mm, accounting for 62.90%. The mineral composition analysis of the sample is shown in Table 1. The main metal oxides of the sample are titanomagnetite, followed by ilmenite. The main metal sulfide is pyrrhotite. The main gangue minerals are labradorite, olivine, and pyroxene. The main useful components of the sample are Fe, TiO 2 and V 2 O 5 The grades are 54.65%, 12.19% and 0.64% respectively.

[0044] 2. Leaching agent preparation: Prepare 25.5% hydrochloric acid solution as the leaching agent.

[0045] 3. Leaching process: The wet-ground iron concentrate was mixed with hydrochloric acid solution at a solid-liquid ratio of 6:1, and leached at a leaching temperature of 92°C, normal pressure, and a stirring speed of 600 r / min for 4 hours.

[0046] 4. Result analysis: Measurement of Fe and V in the leaching solution 2 O 5 and TiO 2 The concentration of Fe was calculated and the leaching rate was 77.24%, V 2 O 5 The leaching rate of TiO 2 The leaching rate is 4.42%.

[0047] Example 2: Mechanically activated wet leaching with ferric chloride and ammonium fluoride as leaching aids

[0048] 1. Sample preparation:

[0049] Same as Comparative Example 1.

[0050] 2. Wet grinding activation:

[0051] Wet grinding was performed using grinding balls of Φ10 mm to 25 mm, with a ball-to-material ratio of 20:1 and a wet grinding time of 1 to 2 hours. During the wet grinding process, 0.3% ferric chloride was added as a grinding aid.

[0052] 3. Preparation of leaching agent: same as Comparative Example 1.

[0053] 4. Leaching process: The wet-ground iron ore concentrate was mixed with hydrochloric acid solution at a solid-liquid ratio of 8:1, and ammonium fluoride (the addition amount was 2% of the mass of the leached material) was added to carry out leaching at a stirring speed of 600 r / min at normal temperature and pressure for 4 hours.

[0054] 5. Result analysis: Measurement of Fe and V in the leaching solution 2 O 5 and TiO 2 The leaching rate was calculated based on the concentration of Fe, which was 80.36% and V 2 O 5 The leaching rate of TiO 2 The leaching rate is 6.77%.

[0055] Implementation case 3: Wet leaching with ammonium fluoride addition

[0056] 1. Sample preparation: same as Comparative Example 1.

[0057] 2. Wet grinding activation: Use Φ10mm~25mm grinding balls for wet grinding, the ball-to-material ratio is 20:1, and the wet grinding time is 1h~2h. During the wet grinding process, add 0.9% ferric chloride as a grinding aid.

[0058] 3. Preparation of leaching agent: same as Comparative Example 1.

[0059] 4. Leaching process: The wet-ground iron ore concentrate was mixed with hydrochloric acid solution at a solid-liquid ratio of 8:1, and ammonium fluoride (the addition amount was 7% of the mass of the leached material) was added. Leaching was carried out at a stirring speed of 600 r / min at normal temperature and pressure for 4 hours.

[0060] 5. Result analysis: Measurement of Fe and V in the leaching solution 2 O 5 and TiO 2 The leaching rate was calculated based on the concentration of Fe and 85.06% of V. 2 O 5 The leaching rate of TiO 2 The leaching rate is 8.25%.

Claims

1. A method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure, characterized in that The steps include: S1. Prepare vanadium-titanium-iron concentrate sample; S2, wet grinding and activating the sample, and adding grinding aids; S3, using hydrochloric acid solution as a leaching agent, mixing the wet-milled sample with the hydrochloric acid solution, and stirring and leaching at normal temperature and pressure; S4. After the leaching is completed, the solid and liquid are separated to obtain the leaching residue and the leaching liquid, and the leaching rate is calculated.

2. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 1, characterized in that: In the step S1, the grinding concentration of the vanadium-titanium magnetite concentrate sample is 60%±7%.

3. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 1, characterized in that: In step S2, grinding balls with diameters of 10 mm to 25 mm are used for wet grinding, the ball-to-material ratio is 20:1, and the wet grinding time is 1 h to 2 h.

4. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 1, characterized in that: The grinding aid added in step S2 is ferric chloride, and the amount of ferric chloride added is 0.5% to 0.9% of the mass of the iron ore concentrate.

5. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 1, characterized in that: In step S3, the initial concentration of the hydrochloric acid solution is 20% to 35%, and deionized water is added to dilute it according to the leaching liquid-to-solid ratio (6 to 10):

1.

6. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 5, characterized in that: In step S3, the initial concentration of hydrochloric acid is 25.5%, the leaching liquid-solid ratio is 8:1, the leaching time is 2h-4h, and the leaching stirring speed rate is 200r / min-600r / min.

7. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 1, characterized in that: In the step S3, a leaching aid needs to be added, and the leaching aid is ammonium fluoride.

8. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 7, characterized in that: The amount of ammonium fluoride added is 1% to 7% of the mass of the leached material.

9. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 1, characterized in that: In step S3, the leaching temperature is maintained at room temperature 25°C ± 2°C, and the leaching time is 2h to 4h under one atmosphere of pressure.

10. The method for separating valuable metals by wet grinding activated hydrochloric acid leaching at room temperature and pressure according to claim 6, characterized in that: In step S3, the stirring speed is set to 500 r / min to 600 r / min at the initial stage of leaching, and gradually decreases to 200 r / min to 250 r / min as the leaching reaction proceeds.