System for obtaining high-purity light burning powder and high-grade magnesium salt by grading and purifying magnesite

Abstract

The utility model provides a system for obtaining high-purity light burning powder and high-grade magnesium salt by grading and purifying magnesite, and relates to the technical field of magnesium salt chemical industry. The device consists of a calcining unit 1, a crushing unit 1, a winnowing and grading unit, a dust remover, a compressor, a hydrator, a suspension separator, a filtering unit 1, a calcining unit 2, a crushing unit 1, a carbonation tower, a filtering separator, a pyrolyzer, a filtering unit 2, a dryer, a crushing unit 2, a calcining unit 3 and a crushing unit 3. The high-silicon low-grade magnesite is sequentially subjected to solid-liquid separation means of crushing, winnowing and grading, hydrocyclone separation after hydration and carbonation, so that the magnesite purification process realizes good and bad classification and optimization of raw materials under the simple, step-by-step and effective principles, and most of low-grade magnesium oxide light calcined powder is separated into high-purity magnesium oxide light calcined powder at low cost; waste residues are separated out, active magnesium oxide, light magnesium carbonate and high-purity magnesium oxide with high additional values are obtained, and the problem of comprehensive utilization of low-grade magnesite is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of magnesium salt chemical industry, in particular to a production system and a process method for obtaining high-purity light-burned magnesium oxide and a series of high-grade industrial magnesium salts with magnesite as the raw material. Background Art

[0002] Light-burned magnesium oxide can be obtained by calcining magnesite. After being crushed, it is transformed into light-burned powder, which has a wide range of industrial uses. High-quality magnesite can obtain light-burned powder with high grade and a good market price. Low-grade magnesite often contains various impurities such as silicon, calcium, and iron, and the obtained light-burned powder is affected accordingly. Its market application and price are restricted, and it is difficult to be purified by simple separation.

[0003] In recent years, with the consumption of high-quality magnesite resources, light-burned powder with a magnesium oxide content higher than 95% has become increasingly scarce in the market, making it difficult to meet the market demand for high-quality high-purity light-burned powder. While the price has been increasing year by year, the market gap has also been increasing year by year. Especially with the breakthrough of the technology of using magnesium oxide to replace ferrosilicon to obtain the main product of metallic magnesium and magnesium aluminate spinel in the smelting of metallic magnesium, there has been an increasing demand for relatively low-cost high-purity light-burned powder. The supply capacity of high-purity light-burned powder has become a key factor restricting the development of the new process for producing metallic magnesium by aluminothermic reduction. Therefore, how to obtain light-burned powder with a relatively high purity from low-grade magnesite has become a hot topic of concern in the current industry.

[0004] In order to broaden the raw material sources, many enterprises use the flotation method to process magnesite to improve its grade and make up for the shortage of supply and cost increase of high-grade magnesite. However, the flotation method for treating magnesite is also restricted by the ore grade. It can only select magnesite ores with relatively high grade, less impurities, and a magnesium oxide content above 45%. For low-grade ores with a magnesium oxide content below 43%, the flotation method has poor effects. And a large amount of flotation agents are used in the flotation of magnesite, generating a large amount of waste residue. These waste residues contain soluble salts of flotation agents, posing potential environmental pollution hazards after being discarded. Therefore, how to efficiently utilize low-grade ores has become a major technical problem.

[0005] By treating dolomite and magnesite through the carbonization process, high-grade basic magnesium carbonate and magnesium oxide with excellent grade and quality can be obtained, which is a basically mature process for producing magnesium salts. However, since this process is an energy-consuming process, the production cost per ton of magnesium oxide is about ten thousand yuan. Obviously, metallic magnesium smelting cannot afford such expensive magnesium oxide, and it can only be purified to more than 95% by a simple method during the process of transforming magnesite into light-burned powder. Summary of the Invention

[0006] The purpose of the present utility model is to provide a system for grading and purifying magnesite to obtain high-purity light-burned powder and high-grade magnesium salts. Based on the comprehensive utilization of the grading treatment of magnesite with high silicon and low grade, more than 95% high-purity light-burned powder can be obtained through air separation, and higher-quality active magnesium oxide can be further obtained by hydrating and hydrocyclone separating low-grade light-burned powder. The remaining light-burned powder hydrate with high impurity content is carbonated to separate out waste residue and further obtain light magnesium carbonate or high-purity magnesium oxide.

[0007] To achieve the above-mentioned invention purpose, the present utility model provides a system for segmental purification of magnesite to obtain high-purity light-burned powder and high-grade magnesium salts, which consists of a calcination 1 unit, a crushing 1 unit, an air separation and grading unit, a dust collector, a compressor, a hydrator, a hydrocyclone separator, a filtration 1 unit, a calcination 2 unit, a crushing 1 unit, a carbonation tower, a filtration separator, a pyrolyzer, a filtration 2 unit, a dryer, a crushing 2 unit, a calcination 3 unit, and a crushing 3 unit. Its structural features and connection relationships are as follows:

[0008] The said calcination 1 unit includes a magnesite powder feed inlet, a combustion gas inlet, a tail gas outlet, and a calcination completed material outlet. The said tail gas outlet is connected to the inlet of the dust collector, and the said calcination completed material outlet is connected to the inlet of the crushing 1 unit;

[0009] The said crushing 1 unit further includes a crushing completed material outlet, which is connected to the inlet of the air separation and grading unit;

[0010] The said air separation and grading unit further includes a light and fine powder outlet and a heavy and coarse powder outlet. The said light and fine powder outlet directly obtains more than 95% high-purity light-burned powder, and the said heavy and coarse powder outlet is connected to the feed inlet of the hydrator;

[0011] The said dust collector further includes a carbon dioxide gas outlet and a fine powder discharge port. The said carbon dioxide gas outlet is connected to the inlet of the compressor, and the said fine powder discharge port is connected to the fine powder feed inlet of the hydrator;

[0012] The said compressor further includes a pyrolyzer carbon dioxide return port and a carbon dioxide gas outlet, which is connected to the carbon dioxide pressure inlet of the carbonation tower;

[0013] The said hydrator further includes a fine powder feed inlet, a filtrate 1 return port, a filtrate 2 return port, and a hydrated slurry discharge port. The said fine powder feed inlet is connected to the fine powder discharge port of the dust collector, the said filtrate 1 return port is connected to the filtrate 1 outlet of the filtration 1 unit, the said filtrate 2 return port is connected to the filtrate 2 outlet of the filtration 2 unit, and the said hydrated slurry discharge port is connected to the feed inlet of the hydrocyclone separator;

[0014] The said hydrocyclone separator further includes an upper hydrocyclone liquid outlet and a lower hydrocyclone liquid outlet. Its upper hydrocyclone liquid outlet is connected to the feeding port of the filtration 1 unit, and its lower hydrocyclone liquid outlet is connected to the feeding port of the carbonation tower;

[0015] The described filtration unit 1 further includes a filter cake discharge port and a filtrate 1 outlet. Its filter cake discharge port is connected to the feed port of the calcination unit 2, and its filtrate 1 outlet is connected to the filtrate 1 return port of the hydrator;

[0016] The described calcination unit 2 further includes a calcined material outlet, which is connected to the feed port of the grinding unit 1;

[0017] The described grinding unit 1 further includes an activated magnesium oxide outlet;

[0018] The described carbonation tower further includes a carbon dioxide inlet and a carbonated finished material outlet. Its carbon dioxide inlet is connected to the compressed carbon dioxide gas outlet of the compressor; its carbonated finished material outlet is connected to the slurry inlet of the filtration separator;

[0019] The described filtration separator further includes a clear liquid outlet and a waste residue discharge port. Its clear liquid outlet is connected to the feed liquid port of the pyrolyzer, and its waste residue port discharges silica sand waste that does not contain soluble salts, is non-toxic, odorless, and has stable properties from the system;

[0020] The described pyrolyzer further includes a finished slurry outlet, which is connected to the slurry feed port of the filtration unit 2;

[0021] The described filtration unit 2 further includes a filter material outlet and a filtrate 2 outlet. Its filter material outlet is connected to the feed port of the dryer, and its filtrate 2 outlet is connected to the filtrate 2 return port of the hydrator;

[0022] The described dryer further includes a dried product discharge port, which is respectively connected to the feed port of the grinding unit 2 and the feed port of the calcination unit 3;

[0023] The described grinding unit 2 further includes a light magnesium carbonate product outlet;

[0024] The described calcination unit 3 further includes a calcined finished material outlet, which is connected to the feed port of the grinding unit 3;

[0025] The described grinding unit 3 further includes a high-purity magnesium oxide product outlet.

[0026] Preferably, the air classification can be in series of multiple stages.

[0027] Preferably, the hydrocyclone separation liquid can be in series of two or more stages.

[0028] Optimally, the described grinding unit 1 further includes a dust outlet, which is connected to a supporting dust collector to reduce dust and capture fine activated magnesium oxide at the same time.

[0029] Similarly, the grinding unit 2 and the grinding unit 3 also include dust outlets, which are connected to the supporting dust collectors to reduce dust and capture fine light magnesium carbonate and high-purity magnesium oxide at the same time.

[0030] Preferably, the calcination unit 1 adopts an internal combustion rotary calciner, which can achieve efficient and stable calcination effect.

[0031] The beneficial effects of the present utility model are as follows: for high-silicon and low-grade magnesite, the means of crushing, air separation and classification, hydrocyclone separation after hydration, and solid-liquid separation of carbonation are successively adopted, so that the magnesite purification process realizes the classification and optimization of raw materials according to quality, the re-classification and optimization of hydration, and the complete separation of waste residue of carbonation under the principles of simplicity, step-by-step and effectiveness. While separating most of the low-grade magnesium oxide light-burned powder into high-purity magnesium oxide light-burned powder at low cost, a part of high-value-added active magnesium oxide products is separated from the remaining low-content light-burned powder by hydrocyclone separation after hydration. Then, the remaining waste (containing magnesium hydroxide in addition to insoluble substances such as silicon dioxide) after hydrocyclone separation is carbonated, so that the effective component magnesium hydroxide is converted into heavy magnesium water, while impurities such as silicon dioxide remain in the solid phase, and the waste residue is removed by solid-liquid separation. The obtained heavy magnesium water is preferably pyrolyzed to obtain basic magnesium carbonate (light magnesium carbonate) filter material, and high-value-added light magnesium carbonate and high-purity magnesium oxide for industrial use are obtained through drying and calcination respectively.

[0032] Compared with the prior art, the present utility model does not adopt flotation agents for ore dressing, and will not cause environmental pollution due to the presence of soluble salts in the flotation agents; in the process of the present utility model, except for separating landfill waste such as stable, non-toxic and odorless silica sand, the appearance of a large number of useless low-content light-burned powder caused by traditional mechanical separation is avoided, and the production cost of high-purity light-burned powder from low-grade magnesite is greatly reduced; in addition to obtaining low-cost high-purity light-burned powder, the present utility model also obtains high-value-added magnesium salt series industrial products, with remarkable economic benefits. Most importantly, it strategically solves the major supply problem of obtaining high-purity light-burned powder required for the smelting of aluminothermic metal magnesium with low-grade magnesite to replace aluminum due to the exhaustion of aluminum resources, which has great social significance for the dominant position of China's metal magnesium industry in the world. Description of the Drawings

[0033] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0034] Figure 1 It is a system composition diagram for the classification and purification of magnesite in the present utility model to obtain high-purity light-burned powder and high-grade magnesium salts.

[0035] In the figure: 1 - calcination unit 1, 2 - crushing unit 1, 3 - air separation and classification unit, 4 - dust collector, 5 - compressor, 6 - hydrator, 7 - hydrocyclone separator, 8 - filtration unit 1, 9 - calcination unit 2, 10 - crushing unit 1, 11 - carbonation tower, 12 - filtration separator, 13 - pyrolyzer, 14 - filtration unit 2, 15 - dryer, 16 - crushing unit 2, 17 - calcination unit 3, 18 - crushing unit 3 are composed. Detailed Embodiments

[0036] In order to make the purpose, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0037] Embodiment 1: A system for obtaining high-purity light burned powder and high-grade magnesium salts by magnesite classification and purification, which consists of a rotary calcination unit 1, a Raymond mill unit 2, an air separation and classification unit 3, a bag filter 4, an air compressor 5, a hydration tank 6, a suspension separator 7, a filter press unit 8, a calcination unit 9, a crushing unit 10, a carbonation tower 11, a filter press 12, a pyrolysis tank 13, a filter press unit 14, a dryer 15, a crushing unit 16, and a calcination unit 17, a crushing unit 18;

[0038] Its characteristics and connection relationships are as follows:

[0039] The rotary calcination unit 1 includes a magnesite powder inlet, a combustion gas inlet, a tail gas outlet, and a calcined finished material outlet. The tail gas outlet is connected to the inlet of the bag filter 4, and the calcined finished material outlet is connected to the inlet of the Raymond mill unit 2;

[0040] The Raymond mill unit 2 further includes a crushed finished material outlet, which is connected to the inlet of the air separation and classification unit 3;

[0041] The air separation and classification unit 3 further includes a light and fine powder outlet and a heavy and coarse powder outlet. The light and fine powder outlet directly obtains 95% high-purity light burned powder, and the heavy and coarse powder outlet is connected to the feed inlet of the hydration tank 6;

[0042] The bag filter 4 further includes a carbon dioxide gas outlet and a fine powder discharge port. The carbon dioxide gas outlet is connected to the inlet of the air compressor, and the fine powder discharge port is connected to the fine powder feed inlet of the hydration tank 6;

[0043] The air compressor 5 further includes a compressed pyrolysis carbon dioxide return port and a carbon dioxide gas outlet, which is connected to the carbon dioxide pressure inlet of the carbonation tower 11;

[0044] The hydration tank 6 further includes a fine powder feed inlet, a filtrate 1 return port, a filtrate 2 return port, and a hydrated slurry discharge port. The fine powder feed inlet is connected to the fine powder discharge port of the bag filter 4, the filtrate 1 return port is connected to the filtrate 1 outlet of the filter 1 unit 8, the filtrate 2 return port is connected to the filtrate 2 outlet of the filter 2 unit 14, and the hydrated slurry discharge port is connected to the feed inlet of the suspension separator 7;

[0045] The described suspension separator further includes an upper swirling liquid outlet and a lower swirling liquid outlet. Its upper swirling liquid outlet is connected to the feeding port of the filtration unit 8, and its lower swirling liquid outlet is connected to the feeding port of the carbonation tower 11;

[0046] The described filtration unit 8 further includes a filter cake discharge port and a filtrate 1 outlet. Its filter cake discharge port is connected to the feeding port of the calcination unit 9, and its filtrate 1 outlet is connected to the filtrate 1 return port of the hydration tank 6;

[0047] The described calcination unit 9 further includes a calcined material outlet, which is connected to the feeding port of the grinding unit 10;

[0048] The described grinding unit 10 further includes an activated magnesium oxide outlet;

[0049] The described carbonation tower 11 further includes a carbon dioxide pressure inlet and a carbonated finished material outlet. Its carbon dioxide pressure inlet is connected to the compressed carbon dioxide gas outlet of the air compressor 5; its carbonated finished material outlet is connected to the slurry inlet of the filter press 12;

[0050] The described filter press 12 further includes a supernatant liquid outlet and a waste residue discharge outlet. Its supernatant liquid outlet is connected to the liquid inlet of the pyrolysis tank 13, and its waste residue outlet discharges the silicon sand waste that does not contain soluble salts, is non-toxic, odorless and has stable performance from the system;

[0051] The described pyrolysis tank 13 further includes a finished slurry outlet, which is connected to the slurry feeding port of the filtration unit 14;

[0052] The described filtration unit 14 further includes a filter material outlet and a filtrate 2 outlet. Its filter material outlet is connected to the feeding port of the dryer 15, and its filtrate 2 outlet is connected to the filtrate 2 return port of the hydration tank 6;

[0053] The described dryer 15 further includes a dried product discharge outlet, which is respectively connected to the feeding port of the grinding unit 16 and the feeding port of the calcination unit 17;

[0054] The described grinding unit 16 further includes a light magnesium carbonate product outlet;

[0055] The described calcination unit 17 further includes a calcined finished material outlet, which is connected to the feeding port of the grinding unit 18;

[0056] The described grinding unit 18 further includes a high-purity magnesium oxide product outlet.

Claims

1. A system for obtaining high-purity light-burned powder and high-grade magnesium salts by classifying and purifying magnesite, which is composed of a calcination unit 1 (1), a pulverizing unit (2), a pneumatic classification unit (3), a dust collector (4), a compressor (5), a hydrator (6), a suspension separator (7), a filtration unit 1 (8), a calcination unit 2 (9), a pulverizing unit 1 (10), a carbonation tower (11), a filtration separator (12), a pyrolyzer (13), a filtration unit 2 (14), a dryer (15), a pulverizing unit 2 (16), a calcination unit 3 (17), and a pulverizing unit 3 (18), and is characterized in that: The said calcination unit 1 (1) includes a magnesite powder inlet, a combustion gas inlet, a tail gas outlet, and a calcination completed material outlet. The said tail gas outlet is connected to the inlet of the dust collector (4), and the said calcination completed material outlet is connected to the inlet of the pulverizing unit (2); The said pulverizing unit (2) further includes a pulverization completed material outlet, and this outlet is connected to the inlet of the pneumatic classification unit (3); The said pneumatic classification unit (3) further includes a light and fine powder outlet and a heavy and coarse powder outlet. The said light and fine powder outlet directly obtains 95% high-purity light-burned powder, and the said heavy and coarse powder outlet is connected to the feed inlet of the hydrator (6); The said dust collector (4) further includes a carbon dioxide gas outlet and a fine powder discharge port. The said carbon dioxide gas outlet is connected to the inlet of the compressor (5), and the said fine powder discharge port is connected to the fine powder feed inlet of the hydrator (6); The said compressor (5) further includes a pyrolyzer carbon dioxide return port and a carbon dioxide gas outlet, and this outlet is connected to the carbon dioxide pressure inlet of the carbonation tower (11); The said hydrator (6) further includes a fine powder feed inlet, a filtrate 1 return port, a filtrate 2 return port, and a hydrated slurry discharge port. The said fine powder feed inlet is connected to the fine powder discharge port of the dust collector (4), the said filtrate 1 return port is connected to the filtrate 1 outlet of the filtration unit 1 (8), the said filtrate 2 return port is connected to the filtrate 2 outlet of the filtration unit 2 (14), and the said hydrated slurry discharge port is connected to the feed inlet of the suspension separator (7); The said suspension separator (7) further includes an upper hydrocyclone outlet and a lower hydrocyclone outlet. Its upper hydrocyclone outlet is connected to the feed port of the filtration unit 1 (8), and its lower hydrocyclone outlet is connected to the feed port of the carbonation tower (11); The said filtration unit 1 (8) further includes a filter cake discharge port and a filtrate 1 outlet. Its filter cake discharge port is connected to the feed inlet of the calcination unit 2 (9), and its filtrate 1 outlet is connected to the filtrate 1 return port of the hydrator (6); The said calcination unit 2 (9) further includes a fired material outlet, and this outlet is connected to the feed inlet of the pulverizing unit 1 (10); The said pulverizing unit 1 (10) further includes an activated magnesium oxide outlet; The said carbonation tower (11) further includes a carbon dioxide pressure inlet and a carbonation completed material outlet. Its carbon dioxide pressure inlet is connected to the compressed carbon dioxide gas outlet of the compressor (5); its carbonation completed material outlet is connected to the slurry inlet of the filtration separator (12); The described filtration and separation machine (12) further includes a clear liquid outlet and a waste residue discharge outlet. The clear liquid outlet is connected to the liquid inlet of the pyrolyzer (13), and the waste residue outlet discharges the silicon sand waste that does not contain soluble salts, is non-toxic, odorless, and has stable properties from the system; The described pyrolyzer (13) further includes a finished slurry outlet, which is connected to the slurry inlet of the filtration unit 2 (14); The described filtration unit 2 (14) further includes a filter material outlet and a filtrate 2 outlet. The filter material outlet is connected to the inlet of the dryer (15), and the filtrate 2 outlet is connected to the filtrate 2 return port of the hydrator (6); The described dryer (15) further includes a dried product discharge outlet, which is respectively connected to the inlet of the pulverization unit 2 (16) and the inlet of the calcination unit 3 (17); The described pulverization unit 2 (16) further includes a light magnesium carbonate product outlet; The described calcination unit 3 (17) further includes a calcination finished material outlet, which is connected to the inlet of the pulverization unit 3 (18); The described pulverization unit 3 (18) further includes a high-purity magnesium oxide product outlet.

2. The system for obtaining high-purity light-burned powder and high-grade magnesium salts by magnesite classification and purification according to claim 1, characterized in that: The described air separation and classification unit (3) is in a 2-stage series connection.

3. The system for obtaining high-purity light-burned powder and high-grade magnesium salts by magnesite classification and purification according to claim 1, characterized in that: The described calcination unit 1 (1) uses an internal combustion rotary calciner.

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