Method for activating bauxite under coal

Abstract

The invention relates to the technical field of efficient utilization of bauxite resources, in particular to an under-coal bauxite activating treatment method which comprises the following steps: adding an activating agent into bauxite, and then performing activating roasting treatment in an activating atmosphere; treating the activated and roasted bauxite by adopting a high-temperature calcification dissolution technology; and carrying out liquid-solid separation on the dissolved-out product to obtain a sodium aluminate solution and the calcified transformed red mud. According to the method, in the activation process, carbon dioxide reacts with carbon in the bauxite to generate carbon monoxide, oxygen is supplemented in good time, heat generated by the reaction of oxygen, carbon monoxide and carbon can meet the reaction requirement, additional energy supply is not needed, and efficient self-supply of energy is achieved. An alkaline compound is added in the activation roasting stage, so that the activation effect can be achieved, and the problems of bauxite inactivation and dissolution efficiency reduction caused by traditional roasting are solved. Meanwhile, a high-temperature calcification dissolution technology is adopted, the dissolution rate is higher than the conventional dissolution rate, and the calcified and dissolved red mud can be used for building materials, soil remediation or soil improvement agents.

Description

Technical Field

[0001] The present invention relates to the technical field of efficient utilization of bauxite resources, in particular to a method for activating bauxite under coal. Background Art

[0002] Sub-coal bauxite refers to the bauxite deposits found beneath coal seams. my country's sub-coal bauxite deposits are primarily found in Shanxi and Henan. Shanxi is a major bauxite-producing province in my country, with sub-coal bauxite deposits widely distributed throughout the province's coal-bearing strata. Henan also boasts abundant sub-coal bauxite resources. In western Henan, the presence of both high-quality bauxite deposits and the presence of above-coal bauxite deposits is common.

[0003] The carbon in underground bauxite originates primarily from coexisting coal seams or coal lines, as well as residual organic matter from the mineralization process. Carbon can exist in the form of organic carbon (such as coal dust and humus) or inorganic carbon (such as carbonate minerals). The carbon content in underground bauxite is typically high, varying depending on the geological conditions of the deposit. Generally, the carbon content ranges from 1% to 10%, with some high-carbon bauxites exceeding 10%. Carbon exists in several forms: Organic carbon, primarily in the form of coal dust and humus, is the primary form of carbon in underground bauxite. Inorganic carbon, present in the form of carbonate minerals (such as calcite and dolomite), is present in relatively low concentrations. The carbon content of underground bauxite is a key factor affecting its resource utilization. High carbon content increases the difficulty of beneficiation and smelting, reducing resource utilization. Physical beneficiation, roasting pretreatment, and chemical treatment can effectively reduce the carbon content and enhance the economic value of underground bauxite.

[0004] Patent CN202311561113.4 discloses a method for in-situ efficient leaching and replacement mining of bauxite under coal, which belongs to the field of energy-efficient green mining technology; by laying wells, fracturing the coal seam, releasing heat through the oxidation-reduction reaction of the coal seam, and using water to extract heat, the hot water obtained by heat exchange is used to prepare a leaching solution, and then the leaching solution is injected into the bauxite layer below the coal seam for in-situ mining of aluminum; this method combines the in-situ mining technology of coal with the in-situ mining technology of bauxite, realizing the clean, green and efficient in-situ mining of coal and bauxite under coal.

[0005] Patent CN202311069696.9 discloses an in-situ high-efficiency electrolytic mining device and method for bauxite under medium and shallow coal, which belongs to the field of underground resource mining technology. It is based on the large amount of heat released by the redox reaction of coal to produce aluminum by in-situ electrolysis of bauxite, thereby realizing the coordinated mining of coal and bauxite; it realizes the joint in-situ mining of coal and bauxite associated with coal seams, solving the problem of the difficulty of underground aluminum mining under coal; it makes full use of the oxygen generated by the electrolysis of the molten alumina-cryolite mixture to assist the redox reaction of the coal seam, forming a closed-loop utilization of resources and saving the operating costs of the system; it has minimal impact on the underground ecological environment and can well protect groundwater resources.

[0006] In summary, the above patents do not involve the comprehensive utilization of bauxite resources under coal. At present, my country still lacks technical solutions for the utilization of bauxite resources under coal. Summary of the Invention

[0007] (1) Technical issues to be resolved

[0008] In view of the problem that the existing technology still lacks solutions for utilizing bauxite resources under coal.

[0009] (2) Technical solution

[0010] To this end, the present invention relates to a method for activating bauxite under coal, comprising:

[0011] Step 1: Add activator to bauxite and perform activation roasting treatment under activation atmosphere;

[0012] Step 2: The activated roasted bauxite is treated by high temperature calcification and dissolution technology;

[0013] Step 3: The dissolved product is subjected to liquid-solid separation to obtain sodium aluminate solution and calcified red mud.

[0014] Furthermore, the activation temperature is controlled to be 500-800° C., and the activation time is controlled to be 3 min to 60 min.

[0015] Furthermore, the activator is a basic compound.

[0016] Furthermore, the activation atmosphere is controlled to introduce at least one of CO2 gas or O2 gas.

[0017] Furthermore, the basic compound is at least one of an alkali metal, an alkaline earth metal oxide, a hydroxide or a carbonate.

[0018] Furthermore, the activation equipment adopts a closed packed bed or a closed rotary kiln, and adopts a negative pressure system to control the vacuum degree to 50-100kPa, wherein the closed packed bed includes: fixed bed, moving bed, fluidized bed, conveying bed, and vibrating fluidized bed.

[0019] Furthermore, in step 2, the activated roasted bauxite is dissolved by a calcination carbonization method, the dissolution temperature is controlled to be greater than 280° C., and the aluminum-silicon ratio of the calcified red mud is less than 1.

[0020] Furthermore, in step 2, the activated roasted bauxite is dissolved by a calcified potash method, the dissolution temperature is controlled to be greater than 280° C., and the aluminum-silicon ratio of the calcified red mud is 0.85-0.90.

[0021] Furthermore, the obtained calcified red mud is modified with nitrogen, phosphorus and potassium, granulated and magnetized, and used as a soil conditioner.

[0022] Furthermore, in step 1, the activated flue gas generated after roasting is treated with zinc oxide for desulfurization to obtain zinc sulfate, which is then treated with calcification and capture to obtain calcium carbonate. The zinc sulfate and calcium carbonate are then treated with desulfurization and decarbonization to obtain combustible coal gas.

[0023] (3) Beneficial effects

[0024] The present invention provides a method for activating bauxite ore beneath coal, comprising: adding an activator to the bauxite and then subjecting it to activation calcination in an activating atmosphere; treating the activated calcined bauxite with a high-temperature calcification and dissolution technique; and subjecting the dissolution product to liquid-solid separation to obtain a sodium aluminate solution and calcified red mud.

[0025] The present application mentions a method for activation treatment of bauxite under coal, which has significant advantages. During the activation treatment, a mixed gas of CO2 and O2 can be used or one of the gases can be used alone. During the activation process, carbon dioxide reacts with the carbon in the bauxite to produce carbon monoxide. Oxygen is added in a timely manner. The heat generated by the reaction of oxygen with carbon monoxide and carbon can meet the reaction requirements, without the need for additional energy supply, and energy-efficient self-sufficiency is achieved. Adding alkaline compounds during the activation roasting stage can play an activation role and avoid the problems of bauxite deactivation and reduced dissolution efficiency caused by traditional roasting. Using high-temperature calcification dissolution technology, the dissolution rate is higher than the theoretical dissolution rate of the conventional Bayer process, and the aluminum-silicon ratio of the generated red mud is lower than 1. These red muds after calcification and dissolution have a wide range of uses and can be used in the production of building materials, as well as in soil remediation or as a soil conditioner. This method achieves efficient utilization of energy and circular development of resources, providing a high-quality solution for the treatment of bauxite under coal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a process flow chart of a method for activation treatment of bauxite under coal mentioned in this application;

[0027] Figure 2 This is another process flow chart of the method for activation treatment of under-coal bauxite mentioned in this application. DETAILED DESCRIPTION

[0028] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0029] When amount, concentration or other value or parameter are represented with range, preferred range or the range that a series of upper preferred value and lower preferred value limit are expressed, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, and no matter whether this scope is disclosed separately.For example, when disclosing scope " 1-5 ", described scope should be interpreted as including scope " 1-4 ", " 1-3 ", " 1-2 ", " 1-2 and 4-5 ", " 1-3 and 5 " etc.When numerical range is described in this article, unless otherwise stated, otherwise this scope is intended to include its end value and all integers and fractions within this range.

[0030] In these embodiments, unless otherwise indicated, the parts and percentages are all measured by mass. "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1g, 3.527g, etc. If we say that the mass parts of component A are a parts and the mass parts of component B are b parts, then it means that the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiplication factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0031] refer to Figure 1 and Figure 2 The present invention relates to a method for activating bauxite under coal, comprising:

[0032] Step 1: Add activator to bauxite and perform activation roasting treatment under activation atmosphere.

[0033] It should be noted that the present application controls the activation temperature at 500-800°C, the activation time is 3min-60min, uses an alkaline compound as an activator, and introduces at least one of CO2 gas or O2 gas as an activation atmosphere, which can effectively decarbonize, desulfurize, and remove organic matter from a large amount of carbon-, sulfur-, and organic-containing bauxite stored under the coal seam. The carbon content of the activated bauxite is less than 0.1%, the sulfur content is less than 0.02%, and the organic matter decomposition rate is greater than 90%, which meets the quality requirements of alumina production for bauxite (carbon <1wt.%, sulfur <0.2wt.%, organic matter decomposition rate >90%), improves the purity of the bauxite, and provides high-quality raw materials for subsequent alumina production.

[0034] The present application adjusts the gas production by adjusting the activation atmosphere. According to the carbon content of the bauxite under the coal seam, the ratio of CO2+O2 in the activation treatment atmosphere can be adjusted to gasify the carbon material into CO and obtain a mixed gas of CO, CO2, and SO2, thereby realizing the effective utilization of the carbon element in the bauxite and improving the resource utilization rate to a certain extent.

[0035] The heat generated by the reaction of O2 with C and CO in the activation atmosphere can meet the heat demand for activation of bauxite under coal, achieve heat self-sufficiency, thereby reducing the input of external energy and lowering the cost of activation treatment.

[0036] It should be noted that the activation equipment utilizes a closed packed bed (including fixed beds, moving beds, fluidized beds, conveyor beds, and vibrating fluidized beds) or a closed rotary kiln, and employs a negative pressure system to maintain a controlled vacuum of 50-100 kPa. This equipment selection and operation method not only ensures efficient activation, but also prevents the leakage of harmful gases through the negative pressure system, thereby improving production safety and environmental friendliness.

[0037] Step 2: The activated roasted bauxite is treated with high temperature calcification dissolution technology

[0038] It should be noted that the high-temperature calcification and dissolution technology used in activated bauxite has a higher dissolution rate than the theoretical dissolution rate of the conventional Bayer process. Whether using the calcification and carbonization method (dissolution temperature > 280°C) or the calcification and potash method (dissolution temperature > 280°C), aluminum can be extracted from bauxite more efficiently, improving the recovery rate of aluminum resources.

[0039] It's important to note that calcified red mud with a low aluminum-silicon ratio can be obtained using different dissolution methods. The aluminum-silicon ratio in the calcified carbonization method is less than 1, while the aluminum-silicon ratio in the calcified potash method is 0.85-0.90. This lower aluminum-silicon ratio means the red mud contains relatively low aluminum, minimizing aluminum loss and facilitating its subsequent comprehensive utilization.

[0040] Step 3: Separate the dissolved product into liquid and solid to obtain sodium aluminate solution and calcified red mud.

[0041] Liquid-solid separation yields a sodium aluminate solution, providing the raw material for subsequent alumina production. Furthermore, calcified red mud can be used in building materials production. For example, red mud obtained through the calcification-carbonization method can be used to produce 525 cement. This achieves resource utilization of red mud, reduces solid waste emissions, and alleviates environmental pressure.

[0042] The red mud obtained by the calcified potash method can be used as a soil conditioner for soil remediation or improvement after nitrogen, phosphorus and potassium modification, granulation and magnetization treatment, further expanding the application field of red mud and improving the comprehensive utilization value of resources.

[0043] In step 1, the activated flue gas produced after roasting is desulfurized with zinc oxide to produce zinc sulfate, which is then calcified and captured to produce calcium carbonate. The zinc sulfate and calcium carbonate are then desulfurized and decarbonized separately to produce combustible gas (CO). This process effectively treats the activated flue gas, reducing emissions of harmful gases such as SO2 while also recovering valuable zinc sulfate and calcium carbonate, producing combustible gas. This improves resource utilization and reduces environmental pollution.

[0044] This application describes a method for activating bauxite ore from coal mines, using a mixture of CO2 and O2, or using either gas alone, to activate the ore. During the activation process, carbon dioxide reacts with carbon in the ore to produce carbon monoxide. Simultaneously, oxygen can be added at appropriate times. The oxygen reacts with the carbon monoxide and carbon in the ore, providing the required heat for the entire reaction process without the need for additional energy, thus achieving efficient energy self-sufficiency. Furthermore, this application incorporates an alkaline compound during the activation and roasting stage of the ore from coal mines. This compound activates the ore during the roasting process, effectively avoiding the deactivation of the ore during conventional roasting and the drawback of reduced dissolution efficiency. Furthermore, this application utilizes high-temperature calcification and dissolution technology, resulting in a dissolution rate higher than the theoretical dissolution rate of the conventional Bayer process, and the resulting red mud has an aluminum-silicon ratio of less than 1. This calcified and dissolved red mud has a wide range of applications, including in building materials production, soil remediation, and as a soil conditioner, achieving efficient resource utilization and circular development.

[0045] To better understand the technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0046] The bauxite under coal in a certain place in Shanxi used in the embodiments of the present application, the alkaline compound is one of the alkali metal or alkaline earth metal compounds such as calcium oxide, calcium carbonate, sodium carbonate, potassium carbonate, etc., and other alkali metal or alkaline earth metal compounds can be used as alkaline oxide raw materials.

[0047] Example 1

[0048] The activation temperature for coal-fired bauxite is 800°C for 3 minutes. Calcium oxide is used as the activator, and a CO2+O2 mixed gas atmosphere is used as the activation atmosphere. The activation equipment utilizes a closed fixed-bed reactor with a negative pressure system and a vacuum degree of 50kPa. The activated bauxite has a carbon content of 0.08%, a sulfur content of less than 0.016%, and an organic matter decomposition rate of 92%. The activated flue gas is desulfurized with zinc oxide to produce zinc sulfate, which is then calcified and captured to produce calcium carbonate. Combustible coal gas (CO) is obtained after desulfurization and decarbonization. The activated bauxite is processed using the calcification-carbonization method: the dissolution temperature is 285°C, the dissolution rate is higher than the theoretical dissolution rate of the Bayer process, and the aluminum-silicon ratio of the calcified red mud is less than 1. The red mud can be used to produce 525 cement.

[0049] Example 2

[0050] The activation temperature for coal-fired bauxite is 500°C for 60 minutes. Potassium carbonate is used as the activator, and a CO2+O2 mixed gas atmosphere is used. The activation equipment can be a closed moving bed with a negative pressure system and a vacuum degree of 80kPa. The activated bauxite has a carbon content of 0.05%, a sulfur content of 0.01%, and an organic matter decomposition rate of 95%. The activated flue gas is desulfurized with zinc oxide to produce zinc sulfate, which is then calcified and captured to produce calcium carbonate. After desulfurization and decarbonization, combustible coal gas (CO) is obtained. The activated bauxite can be processed using the calcification potash method: the dissolution temperature is 282°C, the red mud aluminum-silicon ratio is 0.85, and the dissolution rate is higher than the theoretical dissolution rate of the Bayer process. The resulting red mud is modified with nitrogen, phosphorus, and potassium, granulated, and magnetized, and can be used as a soil conditioner.

[0051] Example 3

[0052] The activation temperature for coal-fired bauxite is 600°C for 10 minutes. Calcium carbonate is used as the activating agent and O2 is used as the activating atmosphere. The activation equipment can be a closed moving bed with a negative pressure system and a vacuum degree of 50kPa. The activated bauxite has a carbon content of 0.06%, a sulfur content of less than 0.01%, and an organic matter decomposition rate of 92%. The activated flue gas is desulfurized with zinc oxide to produce zinc sulfate, which is then calcified and captured to produce calcium carbonate. Combustible coal gas (CO) is obtained after desulfurization and decarbonization. The activated bauxite is processed using the calcification and carbonization method: the dissolution temperature is 286°C, the dissolution rate is higher than the theoretical dissolution rate of the Bayer process, and the aluminum-silicon ratio of the calcified red mud is less than 1. The red mud can be used to produce 525 cement.

[0053] Example 4

[0054] The activation temperature for coal-fired bauxite is 800°C for 40 minutes. Sodium carbonate is used as the activating agent, and a CO2+O2 mixed gas atmosphere is used as the activation atmosphere. The activation equipment can be a closed rotary kiln with a negative pressure system and a vacuum degree of 80kPa. The activated bauxite has a carbon content of 0.08%, a sulfur content of 0.015%, and an organic matter decomposition rate of 94%. The activated flue gas is desulfurized with zinc oxide to produce zinc sulfate, which is then calcified and captured to produce calcium carbonate. Combustible coal gas (CO) is obtained after desulfurization and decarbonization. The activated bauxite is processed using the calcification and carbonization method: the dissolution temperature is 285°C, the dissolution rate is higher than the theoretical dissolution rate of the Bayer process, and the aluminum-silicon ratio of the calcified red mud is less than 1. The red mud can be used to produce 525 cement.

[0055] Example 5

[0056] The activation temperature for coal-fired bauxite is 700°C for 30 minutes. Calcium carbonate is used as the activator, and a CO2+O2 mixed gas atmosphere is used. The activation equipment can utilize a closed conveyor bed and a negative pressure system with a vacuum degree of 50-100 kPa. The activated bauxite has a carbon content of 0.08%, a sulfur content of less than 0.014%, and an organic matter decomposition rate of 92%. The activated flue gas is desulfurized with zinc oxide to produce zinc sulfate, which is then calcified and captured to produce calcium carbonate. Combustible coal gas (CO) is obtained after desulfurization and decarbonization. The activated bauxite is processed using the calcified potash method: the dissolution temperature is 285°C, the red mud has an aluminum-silicon ratio of 0.90, and the dissolution rate exceeds the theoretical dissolution rate of the Bayer process. The resulting red mud undergoes nitrogen, phosphorus, and potassium modification, granulation, and magnetization, and can be used as a soil conditioner.

[0057] The above describes the basic principles, main features, and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any person skilled in the art without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

[0058] In the description of the present invention, each embodiment focuses on the differences from other embodiments, and reference can be made to the same or similar parts between the embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0059] In the description of the present invention, relational terms such as first and second are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined. Moreover, the term "comprises", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the statement "comprising a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements.

[0060] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0061] In the description of this specification, the terms "one embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples" refer to the specific features, structures, materials or characteristics described in conjunction with the embodiment or example and included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0062] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for activation treatment of bauxite under coal, characterized in that: include: Step 1: Add activator to bauxite and perform activation roasting treatment under activation atmosphere; Step 2: The activated roasted bauxite is treated by high temperature calcification and dissolution technology; Step 3: The dissolved product is subjected to liquid-solid separation to obtain sodium aluminate solution and calcified red mud.

2. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: The activation temperature is controlled at 500-800°C, and the activation time is controlled at 3min-60min.

3. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: The activator is a basic compound.

4. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: The activation atmosphere is controlled by introducing at least one of CO2 gas or O2 gas.

5. The method for activation treatment of bauxite under coal according to claim 3, characterized in that: The basic compound is at least one of an alkali metal, an alkaline earth metal oxide, a hydroxide or a carbonate.

6. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: The activation equipment adopts a closed packed bed or a closed rotary kiln and a negative pressure system to control the vacuum degree to 50-100kPa. The closed packed bed includes: fixed bed, moving bed, fluidized bed, conveying bed and vibrating fluidized bed.

7. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: In step 2, the activated calcined bauxite is dissolved by a calcification carbonization method, the dissolution temperature is controlled to be greater than 280° C., and the aluminum-silicon ratio of the calcification-transformed red mud is less than 1.

8. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: In step 2, the activated roasted bauxite is dissolved by a calcified potash method, the dissolution temperature is controlled to be greater than 280° C., and the aluminum-silicon ratio of the calcified red mud is 0.85-0.

90.

9. The method for activation treatment of bauxite under coal according to claim 8, characterized in that: The obtained calcified red mud is modified with nitrogen, phosphorus and potassium, granulated and magnetized, and used as a soil conditioner.

10. The method for activation treatment of bauxite under coal according to claim 1, characterized in that: In step 1, the activated flue gas generated after roasting is treated with zinc oxide for desulfurization to obtain zinc sulfate, which is then treated with calcification and capture to obtain calcium carbonate. The zinc sulfate and calcium carbonate are then treated with desulfurization and decarbonization to obtain combustible coal gas.

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