A method for producing a red mud fire-retardant material and its use

Abstract

The application relates to the field of metallurgical solid waste recycling, in particular to a production method of a red mud flame-retardant material and application thereof; the production method comprises the following steps: separating red mud overflow slurry from red mud slurry, and filtering to obtain red mud filter cake; adding the filter cake into sodium aluminate liquor, and decomposing to obtain sodium aluminate solution decomposition slurry; filtering, washing, drying and grinding the sodium aluminate solution decomposition slurry to obtain a red mud-based flame-retardant material; the production method can obtain the red mud-based flame-retardant material rich in aluminum hydroxide crystals, so that the red mud can effectively replace aluminum hydroxide to serve as a filling raw material of the flame-retardant material, realizes low-cost resource treatment of the red mud, and therefore can realize comprehensive utilization of the red mud and reduce the production cost of aluminum oxide.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metallurgical solid waste recycling, in particular to a production method of red mud flame-retardant material and application thereof. BACKGROUND

[0002] Red mud is a waste produced in the process of extracting alumina from bauxite, and is named for its reddish-brown mud-like appearance. Red mud is the largest waste produced in the process of alumina production, and is also the largest pollution source of alumina production. With the continuous development of bauxite industry, the annual discharge of red mud in China can reach more than 15 million tons at present, and with the new production and capacity expansion of old equipment, the total mass of red mud is increasing. The current treatment method of red mud in bauxite production enterprises is mainly to stack or dump red mud into the deep sea. However, the storage of red mud not only occupies a large amount of land and farmland, consumes a large amount of construction and maintenance costs of the stacking yard, but also the residual alkali liquid in the red mud can penetrate into the underground and cause groundwater pollution. Therefore, in today's society where land resources are becoming increasingly scarce and environmental protection is becoming increasingly important, the comprehensive treatment of red mud has become one of the focuses of people's attention. Due to different production methods and bauxite grades, about 0.5-2.5 tons of red mud are produced per ton of alumina, and 3-4 m 3 of alkali-containing waste liquid is also produced per ton of red mud.

[0003] Due to different content of bauxite, different methods are adopted for alumina production. Red mud can be divided into sintering method red mud, Bayer method red mud and combined method red mud according to different alumina production methods. Among them, the production of bauxite by Bayer method accounts for more than 90% of the world's total production. The Bayer method deals with diaspore and gibbsite type bauxite. The process adopted by the Bayer method is to dissolve high-aluminum and high-iron bauxite with strong alkali NaOH, resulting in high content of alumina, iron oxide and alkali in the produced red mud. Therefore, the main components of Bayer red mud are hematite, sodium aluminosilicate hydrate and nepheline. Sintering method and combined method deal with high-silicon, low-iron, diaspore and kaolinite type bauxite, which produces red mud with high CaO content and low alkali and iron content. At present, diaspore type bauxite is mainly used to produce alumina in China, and the obtained red mud is sintering method and combined method red mud, whose main components are dicalcium silicate and its hydrate. Abroad, the Bayer method is mainly used.

[0004] Because the Pingguo bauxite contains various valuable metals, Pingguo Aluminum Industry Company and Guangxi Metallurgical Research Institute jointly carried out experimental research on direct reduction of iron with Pingguo bauxite as raw material and coal as reducing agent. The process flow is to mix the red mud and coal, make a ball, dry, and then reduce the roasting, and finally magnetically select the sponge iron; at present, GanZhou Nonferrous Institute and other companies use high gradient and high intensity magnetic separator to recover iron in red mud, but have not achieved application, and the investment operation cost is high and the recovery rate is low. The above-mentioned red mud application technology development is largely subject to the problem of red mud alkali and water content, so it has not been well utilized.

[0005] Because the red mud has the disadvantages of high viscosity, high water content, thixotropy, difficult drying, long time, and great difficulty in utilization; in terms of resource utilization of red mud, the domestic aluminum oxide industry has carried out technical research work on the use of red mud to produce cement, red mud to make unburned brick, sintered brick and other new wall materials, use of red mud to make silicon calcium board thermal insulation material, red mud plastic filler, red mud silicon calcium fertilizer, red mud as roadbed material, and extraction of valuable metals such as scandium, titanium and iron from red mud, and some progress has been made, but except for red mud for cement production, other technologies have not realized large-scale utilization of red mud.

[0006] With the development of the plastic industry, the demand for powder fillers has further increased, especially mineral fillers, which are non-renewable resources and in short supply, causing prices to continue to rise, so using solid waste as a filler has a broad market space; although the use of red mud as a flame-retardant plastic filler has been studied for many years, and with the improvement of plastic processing and surface treatment agents, the application of red mud in the plastic industry has made new progress; red mud has a significant thermal stabilizing effect on PVC (polyvinyl chloride), so that when it is used with the stabilizer commonly used in PVC, it has a coordinating effect, thereby making the filled PVC product have many excellent properties, such as anti-aging, good thermal stability, good reinforcing effect, good processing performance, good flame retardancy, and low cost and wide application; however, the use of stabilizers increases the cost of red mud, so how to provide a production method of red mud flame-retardant material to produce flame-retardant material at low cost is a technical problem that needs to be solved at present. SUMMARY

[0007] The present application provides a production method of red mud flame-retardant material to solve the technical problem of increased production cost when red mud is used as a flame-retardant material in the prior art.

[0008] In a first aspect, the present application provides a production method of red mud flame-retardant material, which comprises:

[0009] The red mud overflow slurry in the red mud slurry is separated and filtered to obtain a red mud filter cake;

[0010] The filter cake is added into the sodium aluminate liquor, and is decomposed to obtain a sodium aluminate solution decomposition slurry;

[0011] The sodium aluminate solution decomposition slurry is filtered, washed, dried and ground to obtain the red mud-based flame-retardant material.

[0012] Optionally, the concentration of the red mud overflow slurry is 50 g / L-150 g / L.

[0013] Optionally, the concentration of the red mud overflow slurry is 50 g / L-100 g / L.

[0014] Optionally, the red mud overflow slurry satisfies D50<5 μm.

[0015] Optionally, the red mud overflow slurry satisfies D90<20 μm.

[0016] Optionally, the seed ratio of the sodium aluminate liquor and the red mud filter cake is 1-5.

[0017] Optionally, the first tank temperature of the decomposition is 70℃-90℃, and the last tank temperature of the decomposition is 40℃-60℃.

[0018] Optionally, the decomposition rate of the decomposition is 15%-55%.

[0019] Optionally, the initial ɑk of the sodium aluminate solution decomposition slurry is 1.3-2.5.

[0020] In a second aspect, the application provides an application of the production method of the red mud flame-retardant material, and the application comprises using the red mud flame-retardant material obtained by the production method of the first aspect as a filling raw material for flame-retardant boards.

[0021] Compared with the prior art, the above technical solution provided by the embodiments of the application has the following advantages:

[0022] The production method of the red mud flame-retardant material provided by the embodiments of the application can obtain the sodium aluminate solution decomposition slurry rich in aluminum hydroxide seeds by separating the red mud slurry into underflow slurry and overflow slurry, using the overflow slurry as seeds, adding the sodium aluminate liquor, and decomposing, and can obtain the red mud-based flame-retardant material rich in aluminum hydroxide crystals by subsequent filtering, washing, drying and grinding, so that the red mud-based flame-retardant material can effectively replace aluminum hydroxide as a filling raw material of the flame-retardant material, and the red mud can be treated at low cost, so that the comprehensive utilization of the red mud can be realized, and the production cost of aluminum oxide is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate preferred embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those skilled in the field, based on these drawings, other drawings can also be obtained without creative labor.

[0025] Figure 1 A production method flowchart of the red mud flame-retardant material provided in the embodiments of the present application. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Unless otherwise specifically indicated, all the various raw materials, reagents, instruments and equipment and the like used in the present application can be purchased from the market or can be prepared by the existing methods.

[0028] As shown in Figure 1 The embodiments of the present application provide a production method of a red mud flame-retardant material, and the production method comprises:

[0029] S1. Separating red mud overflow slurry from red mud slurry and filtering to obtain red mud filter cake;

[0030] S2. Adding the filter cake to sodium aluminate liquor and decomposing to obtain sodium aluminate solution decomposition slurry;

[0031] S3. Filtering, washing, drying and grinding the sodium aluminate solution decomposition slurry to obtain a red mud-based flame-retardant material.

[0032] In some optional embodiments, the concentration of the red mud overflow slurry is 50 g / L-150 g / L.

[0033] In the embodiments of the present application, controlling the specific concentration of the red mud overflow slurry can make the decomposition between the sodium aluminate liquor and the red mud overflow slurry complete, so as to obtain a red mud-based flame-retardant material rich in aluminum hydroxide.

[0034] The concentration of the red mud overflow slurry can be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, or 150 g / L.

[0035] In some optional embodiments, the concentration of the red mud overflow slurry is 50 g / L to 100 g / L.

[0036] In the embodiments, by further controlling the specific concentration of the red mud overflow slurry, the decomposition between the sodium aluminate liquor and the red mud overflow slurry can be further complete, so that a sufficient amount of the red mud-based flame retardant material containing aluminum hydroxide is obtained.

[0037] The concentration of the red mud overflow slurry can be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, or 100 g / L.

[0038] In some optional embodiments, the red mud overflow slurry satisfies D50 < 5 μm.

[0039] In some optional embodiments, the red mud overflow slurry satisfies D90 < 20 μm.

[0040] In the embodiments, by controlling the specific particle size distribution of the red mud overflow slurry, the particle size distribution of the red mud overflow slurry can be uniform, so that the surface properties of the red mud overflow slurry can be accurately controlled after the addition of the sodium aluminate liquor, and the resource utilization of the red mud overflow slurry is realized.

[0041] In some optional embodiments, the seed ratio of the sodium aluminate liquor to the red mud filter cake is 1 to 5.

[0042] In the embodiments, by controlling the specific seed ratio of the sodium aluminate liquor to the red mud filter cake, the red mud overflow slurry can be used as a crystal seed, the decomposition efficiency of the sodium aluminate liquor can be adjusted, and a red mud-based flame retardant material containing aluminum hydroxide is obtained.

[0043] The seed ratio can be 1, 2, 3, 4, or 5.

[0044] In some optional embodiments, the first tank temperature of the decomposition is 70℃ to 90℃, and the last tank temperature of the decomposition is 40℃ to 60℃.

[0045] In the embodiments of the present application, the specific first-tank temperature and the specific last-tank temperature of the decomposition are controlled, and by using the stepwise decomposition temperature, the sodium aluminate liquor added with the red mud overflow slurry can be completely decomposed, so that the red mud-based flame-retardant material rich in aluminum hydroxide is obtained.

[0046] The first-tank temperature can be 70℃, can be 75℃, can be 80℃, can be 85℃, or can be 90℃.

[0047] The last-tank temperature can be 40℃, can be 45℃, can be 50℃, can be 55℃, or can be 60℃.

[0048] In some optional embodiments, the decomposition rate of the decomposition is 15% to 55%.

[0049] In the embodiments of the present application, the specific decomposition rate of the decomposition is controlled within the range of the decomposition rate, so that the sodium aluminate liquor added with the red mud overflow slurry can be decomposed to generate sufficient aluminum hydroxide seeds, and thus the red mud-based flame-retardant material is obtained.

[0050] The decomposition rate can be 15%, can be 20%, can be 25%, can be 30%, can be 35%, can be 40%, can be 45%, can be 50%, or can be 55%.

[0051] In some optional embodiments, the initial ak of the sodium aluminate solution decomposition slurry is 1.3 to 2.5.

[0052] In the embodiments of the present application, the specific initial ak of the sodium aluminate solution decomposition slurry is controlled, so that the sodium aluminate solution decomposition slurry can exist stably at room temperature, and thus sufficient aluminum hydroxide seeds can be generated in the decomposition process, and thus sufficient red mud-based flame-retardant material is obtained.

[0053] The initial ak can be 1.3, can be 1.4, can be 1.5, can be 1.6, can be 1.7, can be 1.8, can be 1.9, can be 2.0, can be 2.1, can be 2.2, can be 2.3, can be 2.4, or can be 2.5.

[0054] Based on one general inventive concept, the embodiments of the present application provide an application of a production method of a red mud flame-retardant material, and the application comprises using the red mud flame-retardant material obtained by the production method as a filling raw material for flame-retardant boards.

[0055] The application is realized based on the above production method, and the specific steps of the production method can refer to the above examples. Since the application adopts part or all of the technical solutions of the above examples, it at least has all the beneficial effects brought by the technical solutions of the above examples, and thus will not be described here.

[0056] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods in the following examples without specific conditions are generally determined according to national standards. If there is no corresponding national standard, the general international standard, conventional conditions, or the conditions suggested by the manufacturer are used.

[0057] Example 1

[0058] The red mud slurry is divided into a red mud overflow slurry with a concentration of 50 g / L, wherein the D50 of the overflow slurry is 3 μm and the D90 is 16.5 μm. The filter cake after pressure filtration of the overflow slurry is used as a seed, and is added to a sodium aluminate solution with a seed ratio of 2. The initial alk of the sodium aluminate solution is 1.3. The temperature of the first tank in the decomposition process is controlled at 75 ℃, the temperature of the last tank is controlled at 50 ℃, and the decomposition rate is controlled at 25%. A red mud-based flame-retardant material is obtained after the sodium aluminate solution decomposition slurry is filtered, washed, dried, and ground.

[0059] The oil absorption rate of the flame-retardant material is 29, and the flame-retardant thermal decomposition temperature is 212 ℃.

[0060] Example 2

[0061] The red mud slurry is divided into a red mud overflow slurry with a concentration of 100 g / L, wherein the D50 of the overflow slurry is 4 μm and the D90 is 17.9 μm. The filter cake after pressure filtration of the overflow slurry is used as a seed, and is added to a sodium aluminate solution with a seed ratio of 3.5. The initial alk of the sodium aluminate solution is 1.5. The temperature of the first tank in the decomposition process is controlled at 80 ℃, the temperature of the last tank is controlled at 55 ℃, and the decomposition rate is controlled at 35%. A red mud-based flame-retardant material is obtained after the sodium aluminate solution decomposition slurry is filtered, washed, dried, and ground.

[0062] The oil absorption rate of the flame-retardant material is 28, and the flame-retardant thermal decomposition temperature is 215 ℃.

[0063] Example 3

[0064] The red mud slurry is divided into a red mud overflow slurry concentration of 150 g / L, wherein the D50 of the overflow slurry is 5 μm and the D90 is 19 μm; the filter cake of the overflow slurry after pressure filtration is used as a seed, and the seed is added to a sodium aluminate solution at a seed ratio of 4.5, the initial alk of the sodium aluminate solution is 1.6, the temperature of the first tank in the decomposition process is controlled at 85°C, the temperature of the last tank is controlled at 55°C, and the decomposition rate is controlled at 45%, to obtain a sodium aluminate solution decomposition slurry. After filtration, washing, drying and grinding, the red mud-based flame-retardant material is obtained.

[0065] The oil absorption rate of the flame-retardant material is 27, and the flame-retardant thermal decomposition temperature is 217°C.

[0066] The one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0067] (1) The production method of the red mud flame-retardant material provided in the embodiments of the present application has the advantages of uniform particle size, low oil absorption rate, low cost and good filling effect.

[0068] (2) The production method of the red mud flame-retardant material provided in the embodiments of the present application can effectively reduce the processing cost of the flame-retardant material by using the red mud overflow slurry as a seed.

[0069] (3) The production method of the red mud flame-retardant material provided in the embodiments of the present application can realize wet preparation of the red mud flame-retardant material by adding the red mud overflow slurry as a seed to the sodium aluminate solution, can accurately control the surface properties, and well realizes the resource utilization of the red mud.

[0070] The various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the range described has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0071] In the present application, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the present application, the terms "comprise", "contain" and the like mean "comprise but not limited to". In the present text, the 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 any such actual relationship or order between the entities or operations. In the present text, the "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent: the case of A alone, the case of A and B existing at the same time, and the case of B alone. Wherein A, B can be singular or plural. In the present text, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent: a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, c can be single or multiple.

[0072] The above description is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A method for producing a red mud flame-retardant material, characterized in that, The production method includes: The red mud overflow slurry in the red mud slurry is separated and filtered to obtain red mud filter cake; The filter cake is added to the sodium aluminate concentrate as a seed crystal and then decomposed to obtain a sodium aluminate solution decomposition slurry. The sodium aluminate solution decomposition slurry was filtered, washed, dried and ground to obtain a red mud-based flame retardant material rich in aluminum hydroxide crystals; The concentration of the red mud overflow slurry is 50 g / L to 150 g / L; The red mud overflow slurry meets the requirement that D50 < 5μm; The red mud overflow slurry meets the requirement that D90 < 20 μm; The seed ratio of the sodium aluminate concentrate to the red mud filter cake is 1 to 5. The temperature of the first tank in the decomposition process is 70℃~90℃, and the temperature of the last tank in the decomposition process is 40℃~60℃. The initial αk of the sodium aluminate solution decomposing the slurry is 1.3 to 2.

5.

2. The production method according to claim 1, characterized in that, The concentration of the red mud overflow slurry is 50 g / L to 100 g / L.

3. The production method according to claim 1, characterized in that, The decomposition rate is 15% to 55%.

4. The application of a method for producing red mud flame-retardant materials, characterized in that, The application includes using the red mud flame retardant material obtained by the production method according to any one of claims 1-3 as a filling material for flame retardant boards.

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