Method for preparing magnesium oxide raw material from dolomite ore

Abstract

The invention provides a method for preparing a magnesium oxide raw material from dolomite ore, which comprises the following steps: providing a dolomite raw material, and calcining the dolomite raw material to obtain dolomite calcined powder; in an ammonium salt solution containing organic acid radicals, the dolomite calcined powder is subjected to leaching and sedimentation treatment, and filtrate and filter residues are obtained; and washing and drying the filter residues to obtain the magnesium oxide raw material. According to the method, calcium and magnesium in the dolomite can be effectively separated, the high-quality magnesium oxide raw material is prepared, and meanwhile, the method is easy to realize industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of dolomite material processing, and in particular to a method for preparing magnesium oxide raw material by utilizing dolomite ore. Background Art

[0002] Dolomite is a common white non-metallic mineral, and its chemical composition is mainly CaCO3 and MgCO3. It is a composite carbonate mineral. In my country, the reserves of dolomite are very rich, and it is an important calcium and magnesium resource. It is not only widely distributed in my country, but also its raw material quality is generally high. As a filler, it has been widely used in many fields, and its application range is still expanding.

[0003] At the current stage, the development and application of dolomite is mainly at the primary stage, that is, through the preliminary processing of minerals, metallurgical flux with relatively low added value and low-quality light magnesium carbonate are produced. This simple processing method not only fails to give full play to the potential value of the rich calcium and magnesium resources in dolomite, but also causes a huge waste of resources. At the same time, due to the low added value of the product, the profit margin of the enterprise has also been severely compressed, affecting the overall development of the industry. Therefore, separating calcium and magnesium in dolomite is a simple and feasible method to increase the added value of dolomite products, which can not only maximize the potential of dolomite resources, but also significantly improve the economic benefits of enterprises and promote the upgrading and development of the entire industry.

[0004] The existing methods for separating calcium and magnesium from dolomite all have their own drawbacks and shortcomings, as follows:

[0005] The carbonization method requires two carbonization steps, has a complex process, high energy consumption, and requires large equipment investment, thus increasing production costs.

[0006] The acid hydrolysis method consumes a large amount of acid, resulting in a significant increase in production costs, and the waste liquid is prone to pollution, making it unsuitable for large-scale industrial production.

[0007] The ammonium leaching method mainly uses inorganic strong acid ammonium salt to leach the calcined and digested dolomite ash and finally precipitate the magnesium. However, the purity of the products reported so far is not high, and the efficiency, cost and environmental impact in practical applications need to be further improved and evaluated.

[0008] Patent 202211265206.8 discloses a method for co-producing high-quality calcium carbonate and magnesium building materials from dolomite ore. The patent focuses on the preparation of high-purity calcium carbonate. The purity of the byproduct magnesium oxide is not high, and it is mainly used as a building material raw material. Specifically, dolomite is calcined at high temperature and carbon dioxide gas is recovered, and then the calcined powder is subjected to selective precipitation reaction treatment with ammonium salts such as ammonium sulfate. The filtrate obtained by filtration is subjected to carbonation treatment to obtain a calcium carbonate product with a purity of more than 98%, and the filter residue is a magnesium building material raw material-active magnesium oxide. In this process, ammonium sulfate is used to selectively precipitate the calcined dolomite powder. The solubility of calcium sulfate is limited, and solid magnesium sulfate will be produced, resulting in the presence of undissolved calcium sulfate and solid magnesium sulfate in the magnesium oxide filter residue. Although this impure product is no problem as a building material, this method is not feasible for the demand field that requires high-quality magnesium oxide. Patent 201610023391.8 discloses a method for preparing nano magnesium oxide using dolomite as a raw material and an ammonium sulfate leaching method. Specifically, dolomite is calcined and ground into dolomite powder, then mixed with ammonium sulfate solution, heated and stirred reaction is carried out until ammonia water is distilled out to obtain magnesium sulfate solution, then magnesium sulfate solution and ammonia water are respectively mixed with the solution of same volume, then an equivalent amount of magnesium sulfate solution and ammonia water are taken and an equivalent amount of water dilution is added respectively, no dispersant is added or a dispersant is added to magnesium sulfate solution and stirred, concentrated ammonia water is added to ammonia water and stirred and then added dropwise to magnesium sulfate solution, heated and stirred reaction, the magnesium hydroxide white precipitate generated is subjected to ageing, filtration, washing, drying, grinding to obtain magnesium hydroxide white powder, and nano magnesium oxide is obtained by calcining. As can be seen from this, this process is very complicated, and the powder after calcination needs to be heated to more than 120 degrees (120~180 ℃) to mix with ammonium sulfate solution, so as to steam ammonia gas, which consumes energy. And in the step of generating magnesium hydroxide, dispersants such as sodium dodecyl sulfate (SDS) are used, which not only increases the introduction of impurities, causes the increase of cost, but also is carried out by the mode of dropwise addition, is not suitable for industrialized production.

[0009] If the calcium and magnesium in dolomite ore can be effectively separated and high-purity magnesium oxide can be prepared, it can be used in the fields of communications, medicine, precision instruments, etc., which can greatly increase the added value of dolomite, and the cost is low and the product value is high.

[0010] Therefore, how to separate calcium and magnesium from dolomite by a simple and effective method to prepare high-quality magnesium oxide and calcium products, thereby broadening the application range of the products, is the main problem solved by the present invention. Summary of the invention

[0011] In view of the defects in the prior art, the object of the present invention is to provide a method for preparing magnesium oxide raw material using dolomite ore.

[0012] The present invention provides a method for preparing magnesium oxide raw material by using dolomite ore, the method comprising:

[0013] Providing a dolomite raw material, and calcining the dolomite raw material to obtain calcined dolomite powder;

[0014] In an ammonium salt solution containing organic acid radicals, the dolomite calcined powder is subjected to leaching and sedimentation treatment to obtain a filtrate and a filter residue;

[0015] The filter residue is washed and dried to obtain magnesium oxide raw material.

[0016] Optionally, the dolomite raw material is provided, wherein: the mesh number of the dolomite raw material is above 50 meshes.

[0017] Optionally, the dolomite raw material is calcined, wherein: the calcination temperature is 900-1250° C., and the calcination time is 0.5-4 h.

[0018] Optionally, the dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the ammonium salt containing organic acid radicals is a weak acid and weak base salt.

[0019] Optionally, the dolomite calcined powder is leached and precipitated in an ammonium salt solution containing organic acid radicals, wherein the ammonium salt containing organic acid radicals is any one or more of ammonium citrate, ammonium tartrate, ammonium formate and ammonium succinate.

[0020] Optionally, the dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the mass ratio of deionized water to all solid components is 3:1 to 20:1.

[0021] Optionally, the dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the molar ratio of ammonium radicals in the ammonium salt solution to calcium in the dolomite calcined powder is 2:1 to 5:1.

[0022] Optionally, the dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the treatment temperature is 10-60°C.

[0023] Optionally, the dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein: the stirring speed is 200-500 r / min, and the reaction time is 10-60 min.

[0024] Optionally, the filter residue is washed and dried, wherein the drying temperature is 60-100° C. and the drying time is 12-24 hours.

[0025] The present invention decomposes calcium carbonate and magnesium carbonate in dolomite into calcium oxide and magnesium oxide respectively by calcining, and reacts in an ammonium salt solution containing organic acid radicals, and controls the molar ratio of ammonium ions to calcium according to the difference in thermodynamic formation constants of organic acid calcium and organic acid magnesium (the formation constant of organic acid calcium is much greater than that of organic acid magnesium), so that organic acid radicals preferentially complex calcium ions to generate organic acid calcium, and utilizes the characteristic of super solubility of organic acid calcium to dissolve calcium and immerse it in the solution, while ensuring that magnesium oxide does not dissolve, thereby realizing calcium-magnesium separation, and filtering the obtained filter residue to be magnesium oxide. The calcium ions in the solution can be directly used to prepare organic acid calcium products or other products later.

[0026] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0027] 1. The method provided by the present invention can prepare magnesium oxide raw materials through only two steps of calcination and liquid phase leaching, which solves the problem of complex calcium and magnesium separation process and high cost in the traditional dolomite ore processing and application process. The method provided by the present invention has a simple calcium and magnesium separation process and low cost, is conducive to research and large-scale production, and is easy to realize industrial production.

[0028] 2. The present invention can effectively separate calcium and magnesium in dolomite to prepare high-quality magnesium oxide raw materials. The various indicators of the magnesium oxide raw materials prepared by the method of the present invention are controllable, and meet the indicators of 85 powder superior products in the standard "Light-burned magnesium oxide for magnesia products" (WB / T1019-2002), that is, the magnesium oxide content is 85-95%, which meets the requirements for preparing high-end magnesium oxide related materials.

[0029] 3. The present invention can make full use of abundant resources such as various dolomite mines, tailings and dolomite waste slag generated in industrial processes. The diversified selection of raw materials can not only improve the flexibility of the production process, but also provide strong support for the efficient utilization of resources and the development of a circular economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 This is a schematic diagram of a process flow of a method for preparing magnesium oxide raw material using dolomite ore in one embodiment of the present invention;

[0032] Figure 2 The scanning electron microscope characterization result of the calcined dolomite powder in Example 1 of the present invention;

[0033] Figure 3 is the XRD spectrum of the calcined dolomite powder in Example 1 of the present invention;

[0034] Figure 4 In the figure, (a) is the scanning electron microscope characterization result of the magnesium oxide raw material prepared in Example 2 of the present invention, and (b) is Figure 4 (a) A magnified scanning electron microscope image of the magnesium oxide raw material;

[0035] Figure 5 is the XRD spectrum of the magnesium oxide raw material prepared in Example 2 of the present invention;

[0036] Figure 6 In the figure, (a) is the specific surface analysis test curve of the calcined dolomite powder in Example 1 of the present invention, and (b) is the specific surface analysis test curve of the magnesium oxide raw material prepared in Example 4. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0038] In order to solve the problems of low quality, high energy consumption and complex process in dolomite calcium and magnesium separation technology, the embodiment of the present invention provides a simple and efficient method for preparing high-quality magnesium oxide raw material using dolomite ore. Figure 1 , a method for preparing magnesium oxide raw material using dolomite ore provided by an embodiment of the present invention comprises:

[0039] S1. providing dolomite raw material, calcining the dolomite raw material to obtain dolomite calcined powder;

[0040] S2. In an ammonium salt solution containing organic acid radicals, selectively leaching and settling dolomite calcined powder to obtain a filtrate and a filter residue, wherein the filter residue is composed of magnesium oxide;

[0041] S3, washing the filter residue and drying it to obtain magnesium oxide raw material.

[0042] The embodiment of the present invention can prepare magnesium oxide raw materials by only two steps of calcination and liquid phase leaching. By the method of calcination first and then liquid phase reaction, the problem of complex calcium and magnesium separation process and high cost in the traditional dolomite ore processing and application process is solved, and calcium and magnesium in dolomite can be effectively separated to prepare high-quality magnesium oxide raw materials. The preparation process is simple, the product purity is high, and the application range of magnesium oxide products can be broadened. At the same time, the method in the embodiment of the present invention is easy to realize the industrial production of magnesium oxide raw materials.

[0043] Considering that too large a mesh size of dolomite will lead to incomplete calcination, resulting in over-burning of the inner layer and incomplete calcination of the outer layer, which will affect subsequent processing, in some embodiments, the mesh size of the dolomite raw material is above 50 meshes.

[0044] The components of the calcined dolomite powder are calcium oxide and magnesium oxide. When the calcination temperature is too low and the calcination time is too short, the thermal decomposition is incomplete. When the calcination temperature is too high and the calcination time is too long, not only the energy consumption is increased, but also the activity is reduced. Preferably, the calcination temperature is 900-1250°C and the calcination time is 0.5-4h.

[0045] In step S2, calcined dolomite powder is added to deionized water, and under the conditions of preset temperature and speed stirring, ammonium salt containing organic acid radicals is added to react for a period of time, and the molar ratio of ammonium radical ions to calcium is controlled so that the organic acid radicals preferentially complex calcium ions to generate organic acid calcium; the super solubility of organic acid calcium is utilized to dissolve calcium and immerse it in the solution, while ensuring that magnesium oxide is not dissolved, thereby achieving calcium and magnesium separation, and filtering and washing are performed after the reaction is completed, the organic acid calcium enters the filtrate, and the filter residue is magnesium oxide.

[0046] In some embodiments, the ammonium salt containing an organic acid radical is a weak acid and weak base salt.

[0047] Preferably, the ammonium salt containing an organic acid radical is any one or more of ammonium citrate, ammonium tartrate, ammonium formate and ammonium succinate.

[0048] In some embodiments, the mass ratio of deionized water to all solid components, i.e., the liquid-to-solid ratio, is 3:1 to 20:1. The molar ratio of ammonium in the ammonium salt solution to calcium in the calcined dolomite powder is 2:1 to 5:1.

[0049] In some embodiments, during the leaching and sedimentation treatment, the treatment temperature is 10 to 60° C., the stirring speed is 200 to 500 r / min, and the reaction time is 10 to 60 min.

[0050] In some embodiments, the drying temperature is 60-100° C. and the drying time is 12-24 hours, thereby obtaining a dry magnesium oxide raw material.

[0051] Compared with the acid hydrolysis method, the ammonia produced in the ammonium leaching method can be recycled, causing less pollution to the environment. In addition, the overflow of ammonia produced during the reaction can promote the forward progress of the reaction and improve the leaching efficiency.

[0052] In the above embodiment of the present invention, the selection of organic acid ammonium salts such as ammonium citrate and ammonium tartrate is based on the difference in thermodynamic formation constants of the corresponding calcium salts and magnesium salts (such as calcium citrate and magnesium citrate), that is, the formation constant of the corresponding calcium salt is much larger than the formation constant of the corresponding magnesium salt, so that the corresponding calcium salt is preferentially generated during the reaction, and magnesium oxide basically does not participate in the reaction, thereby being retained in the filter residue.

[0053] In the above-mentioned embodiments of the present invention, a suitable liquid-to-solid ratio, a molar ratio of ammonium ion to calcium, and implementation conditions (temperature, stirring speed, time, drying temperature, etc.) are selected to achieve the effect of improving the extraction efficiency and product purity while reducing the cost.

[0054] Compared with the prior art (such as patent application numbers 202211265206.8 and 201610023391.8) using strong acid and strong base ammonium salts such as ammonium sulfate for leaching, the embodiment of the present invention uses organic acid ammonium salts such as ammonium citrate to selectively settle dolomite calcined powder. Taking ammonium citrate as an example, calcium citrate relies on multiple coordination bonds to form a stable chelate, and its stability is much better than calcium sulfate; excess citrate will increase the solubility of calcium citrate, making the leaching efficiency higher and improving the degree of calcium-magnesium separation; ammonium citrate, as a weak acid and weak base salt, has reversible processes such as hydrolysis, which can play a role in pH buffering, and the citric acid-calcium citrate interaction increases the diffusion rate of citric acid and calcium citrate in the solution. The concentration gradient of calcium citrate can drive a large amount of citric acid to diffuse in a countercurrent coupled flow. According to the shrinking core model, calcium citrate diffuses outward while driving citrate to diffuse inward, thereby greatly improving the leaching efficiency. The principles of other ammonium salts containing organic acid radicals such as ammonium tartrate and ammonium formate are similar to those of ammonium citrate and will not be elaborated in detail.

[0055] In the above-mentioned embodiment of the present invention, magnesium oxide raw material can be prepared by only two steps of calcination and liquid phase leaching, which solves the problem of complex process and high cost of calcium-magnesium separation in the traditional dolomite ore processing and application. The method provided by the embodiment of the present invention has a simple calcium-magnesium separation process and low cost, is conducive to research and large-scale production, and is easy to realize industrial production.

[0056] The above-mentioned embodiment of the present invention can effectively separate calcium and magnesium in dolomite to prepare high-quality magnesium oxide raw materials. The various indicators of the magnesium oxide raw materials prepared by the method in the above-mentioned embodiment of the present invention are controllable, and meet the indicators of 85 powder superior products in the standard "Light-burned magnesium oxide for magnesia products" (WB / T1019-2002), that is, the magnesium oxide content is 85-95%, which meets the requirements for preparing high-end magnesium oxide related materials; and the prepared magnesium oxide raw material has a large specific surface area, has a high application value, and has good application prospects.

[0057] The method provided by the above-mentioned embodiment of the present invention can make full use of abundant resources such as various dolomite mines, tailings and dolomite waste slag generated in industrial processes. The diversified selection of raw materials can not only improve the flexibility of the production process, but also provide strong support for realizing efficient utilization of resources and the development of circular economy.

[0058] The scheme of the present application will be explained below in conjunction with specific embodiments and comparative examples. It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the literature in this area or the product specification are carried out. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained through commercial channels.

[0059] Example 1

[0060] The method for preparing magnesium oxide raw material by using dolomite ore provided in an embodiment of the present invention comprises the following steps:

[0061] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder. The morphology of the obtained dolomite calcined powder was analyzed by scanning electron microscopy. The results are as follows: Figure 2 As shown in the figure, the calcined dolomite powder is in the shape of prisms. The composition of the calcined dolomite powder was analyzed by X-ray diffraction, and the results are as follows: Figure 3 As shown, the prepared dolomite calcined powder is a mixture of calcium oxide and magnesium oxide, with a content of 60.6% calcium oxide and 39.4% magnesium oxide. Figure 6 As shown in Figure 2, the specific surface area of ​​calcined dolomite powder is 18.2 m 2 / g.

[0062] S2. Under the condition of a liquid-to-solid ratio (mass ratio of deionized water to all solid components) of 15:1, the above-mentioned dolomite calcined powder and ammonium formate are mixed at a molar ratio of ammonium ion to calcium of 2:1, the treatment temperature is 25°C, the stirring speed is 300r / min, and after reacting for 15 minutes, the filter is filtered to obtain a filter residue.

[0063] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0064] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 90%. According to BET test, the specific surface area of ​​magnesium oxide is 80.0m 2 / g.

[0065] Example 2

[0066] The method for preparing magnesium oxide raw material by using dolomite ore provided in an embodiment of the present invention comprises the following steps:

[0067] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0068] S2. Under the condition of liquid-solid ratio of 10:1, the above-mentioned dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 4:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain the filter residue.

[0069] S3. The filter residue was washed with water and then placed in an oven at 80°C for 12 hours for drying to obtain a raw material of magnesium oxide. The morphology of the obtained magnesium oxide was analyzed by scanning electron microscopy. The results are as follows: Figure 4 As shown in the figure, the magnesium oxide particles are complete and spherical. The composition of magnesium oxide was analyzed by X-ray diffraction, and the results are as follows Figure 5 As shown, the prepared magnesium oxide raw material is relatively pure and has no other impurity peaks.

[0070] According to ICP test, the content of magnesium oxide in magnesium oxide raw material is 93%. According to BET test, the specific surface area of ​​magnesium oxide is 89.7m 2 / g.

[0071] Example 3

[0072] The method for preparing magnesium oxide raw material by using dolomite ore provided in an embodiment of the present invention comprises the following steps:

[0073] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0074] S2. Under the condition of a liquid-solid ratio of 5:1, the above-mentioned dolomite calcined powder and ammonium tartrate are mixed at a molar ratio of ammonium ion to calcium of 3:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain a filter residue.

[0075] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0076] According to ICP test, the content of magnesium oxide in magnesium oxide raw material is 91%. According to BET test, the specific surface area of ​​magnesium oxide is 75.2m 2 / g.

[0077] Example 4

[0078] The method for preparing magnesium oxide raw material by using dolomite ore provided in an embodiment of the present invention comprises the following steps:

[0079] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0080] S2. Under the condition of a liquid-solid ratio of 5:1, the above-mentioned dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 4:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain a filter residue.

[0081] S3, the filter residue is washed with water, and then placed in an oven at 80°C for 12 hours for drying to obtain a magnesium oxide raw material, such as Figure 6 As shown, the specific surface area of ​​magnesium oxide raw material is 95.2m 2 / g.

[0082] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 93%.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing magnesium oxide raw material using dolomite ore, comprising the following steps:

[0085] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0086] S2. Under the condition of a liquid-solid ratio of 2:1, the above-mentioned dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 4:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain a filter residue.

[0087] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0088] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 40%.

[0089] Comparative Example 2

[0090] This comparative example provides a method for preparing magnesium oxide raw material using dolomite ore, comprising the following steps:

[0091] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0092] S2. Under the condition of a liquid-solid ratio of 25:1, the above-mentioned dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 4:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain a filter residue.

[0093] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0094] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 62%.

[0095] Comparative Example 3

[0096] This comparative example provides a method for preparing magnesium oxide raw material using dolomite ore, comprising the following steps:

[0097] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0098] S2. Under the condition of a liquid-solid ratio of 10:1, the above-mentioned dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 1:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain a filter residue.

[0099] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0100] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 55%.

[0101] Comparative Example 4

[0102] This comparative example provides a method for preparing magnesium oxide raw material using dolomite ore, comprising the following steps:

[0103] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0104] S2. Under the condition of a liquid-solid ratio of 10:1, the above-mentioned dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 6:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain a filter residue.

[0105] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0106] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 63%.

[0107] Comparative Example 5

[0108] This comparative example provides a method for preparing magnesium oxide raw material using dolomite ore, comprising the following steps:

[0109] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.2m 2 / g.

[0110] S2. Under the condition of liquid-solid ratio of 10:1, the above dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 4:1, the treatment temperature is 65°C, the stirring speed is 350r / min, and after reacting for 10 minutes, the filter is filtered to obtain the filter residue.

[0111] S3. The filter residue is washed with water, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0112] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 50%.

[0113] Comparative Example 6

[0114] This comparative example provides a method for preparing magnesium oxide raw material using dolomite ore, comprising the following steps:

[0115] S1. Put 500g of dolomite powder with a mesh size of 200 into a muffle furnace and calcine it at 1000℃ for 1h to obtain dolomite calcined powder with a specific surface area of ​​18.224m 2 / g.

[0116] S2. Under the condition of liquid-solid ratio of 10:1, the above dolomite calcined powder and ammonium citrate are mixed at a molar ratio of ammonium ion to calcium of 4:1, the treatment temperature is 20°C, the stirring speed is 350r / min, and after reacting for 80 minutes, the filter is filtered to obtain the filter residue.

[0117] S3. The filter residue is washed with alcohol, and then placed in an oven at 80° C. for 12 hours for drying to obtain a magnesium oxide raw material.

[0118] According to ICP test, the content of magnesium oxide in the magnesium oxide raw material is 63%.

[0119] Table 1 Magnesium oxide yield and magnesium oxide content in each embodiment and comparative example

[0120]

[0121] In Table 1, *magnesium oxide yield is the ratio of the mass of magnesium oxide in the filter residue of step (3) to the mass of magnesium oxide in the dolomite calcined powder of step (2).

[0122] By analyzing Table 1 above, it can be seen that in Comparative Example 1, when the liquid-to-solid ratio is too small, part of the organic acid calcium is not dissolved in the liquid, resulting in an impure product; in Comparative Example 2, when the liquid-to-solid ratio is too large, part of the magnesium oxide is dissolved, resulting in a reduced yield; in Comparative Example 3, when the molar ratio of ammonium to calcium is too small, the calcium oxide cannot be completely converted into a soluble organic calcium salt, resulting in an impure product; in Comparative Example 4, when the molar ratio of ammonium to calcium is too large, excess ammonium ions will chelate with magnesium ions, resulting in a reduced yield; in Comparative Example 5, when the treatment temperature is too high, the organic calcium salt is prone to precipitation, affecting the leaching effect, resulting in an impure product; in Comparative Example 6, when the treatment time is too long, the magnesium oxide undergoes a digestion reaction to generate magnesium hydroxide, resulting in an impure product and a reduced yield.

[0123] In summary, when the liquid-to-solid ratio and the molar ratio of ammonium ion to calcium are too small or too large, the treatment temperature is too high, or the treatment time is too long, the yield or purity of magnesium oxide decreases, which is not conducive to cost reduction and large-scale production.

[0124] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A method for preparing magnesium oxide raw material using dolomite ore, characterized in that: include: Providing a dolomite raw material, and calcining the dolomite raw material to obtain calcined dolomite powder; In an ammonium salt solution containing organic acid radicals, the dolomite calcined powder is subjected to leaching and sedimentation treatment to obtain a filtrate and a filter residue; The filter residue is washed and dried to obtain magnesium oxide raw material.

2. The method for preparing magnesium oxide raw material using dolomite ore according to claim 1, characterized in that: The dolomite raw material is provided, wherein: the mesh number of the dolomite raw material is above 50 meshes.

3. The method for preparing magnesium oxide raw material using dolomite ore according to claim 1, characterized in that: The dolomite raw material is calcined, wherein the calcination temperature is 900-1250° C. and the calcination time is 0.5-4 hours.

4. The method for preparing magnesium oxide raw material using dolomite ore according to claim 1, characterized in that: The dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the ammonium salt containing organic acid radicals is a weak acid and weak base salt.

5. The method for preparing magnesium oxide raw material by utilizing dolomite ore according to claim 1 or 4, characterized in that: The dolomite calcined powder is leached and precipitated in an ammonium salt solution containing organic acid radicals, wherein the ammonium salt containing organic acid radicals is any one or more of ammonium citrate, ammonium tartrate, ammonium formate and ammonium succinate.

6. The method for preparing magnesium oxide raw material using dolomite ore according to claim 1, characterized in that: The dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the mass ratio of deionized water to all solid components is 3:1 to 20:

1.

7. The method for preparing magnesium oxide raw material using dolomite ore according to claim 1, characterized in that: The dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the molar ratio of ammonium radicals in the ammonium salt solution to calcium in the dolomite calcined powder is 2:1 to 5:

1.

8. The method for preparing magnesium oxide raw material using dolomite ore according to claim 1, characterized in that: The dolomite calcined powder is subjected to leaching and sedimentation treatment in an ammonium salt solution containing organic acid radicals, wherein the treatment temperature is 10-60°C.

9. The method for preparing magnesium oxide raw material by utilizing dolomite ore according to claim 1, characterized in that: The dolomite calcined powder is subjected to leaching and sedimentation treatment in the ammonium salt solution containing organic acid radicals, wherein the stirring speed is 200-500 r / min and the reaction time is 10-60 min.

10. The method for preparing magnesium oxide raw material by using dolomite ore according to claim 1, characterized in that: The filter residue is washed and dried, wherein the drying temperature is 60-100° C. and the drying time is 12-24 hours.

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