Gold tailing unfired haydite and its preparation method

Abstract

The application provides a kind of gold tailings baking-free haydite and a preparation method thereof, by mixing gold tailings, cement and neutralization slag according to predetermined mass ratio with hydrogen peroxide solution to prepare a mixture containing a ball core; the mixture is transferred into a balling device, hydrogen peroxide solution is added for balling, the prepared material ball is screened, and the material ball with a diameter of 10-20 mm and a water content of 20-30% is selected as a wet green ball; the wet green ball is placed in a steam curing cellar for curing to obtain the gold tailings baking-free haydite. The application uses gold tailings as the main raw material, acid mine wastewater neutralization slag as the binder and activator, and hydrogen peroxide as the foaming agent, and through processes such as granulation and curing, the haydite baked by solid waste has excellent performance, has the advantages of high preparation efficiency and low cost, realizes the full resource utilization of gold tailings and acid mine wastewater treatment neutralization slag, and has good economic, environmental and social benefits.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and comprehensive solid waste management technology, and in particular to a non-fired ceramsite for gold tailings and its preparation method. Background Technology

[0002] Gold mining and production can drive economic development, but it also generates a large amount of tailings. Gold tailings are solid waste produced after gold ore is processed through beneficiation or gold extraction processes. Their chemical composition includes silicon dioxide, aluminum oxide, and potassium oxide. Statistics show that my country has accumulated 1.298 billion tons of gold tailings. However, on the other hand, my country's gold tailings are not effectively recycled and utilized, with a utilization rate of only 18.9%. Currently, the main method of disposing of gold tailings is to pile them up in tailings ponds, occupying a large amount of land resources and polluting the atmosphere, surface water, and groundwater under natural conditions such as wind and rain. With the continuous discharge of tailings and the increasing height of tailings dams, safety hazards also arise. Therefore, realizing the resource utilization of gold tailings is urgent. Currently, the main ways to comprehensively utilize gold tailings are to recover valuable metals, produce building materials, and use them as mine filler materials, with 43% of tailings used for building material production.

[0003] Sulfur-rich deposits in non-ferrous metal mines contain a large amount of sulfide minerals. Under the influence of air, water, and microorganisms, these minerals undergo a series of reactions including weathering, leaching, oxidation, and hydrolysis, gradually forming acidic liquids containing sulfuric acid, causing serious pollution to the surrounding environment. Currently, most acidic mine wastewater is treated using chemical methods, generating a large amount of neutralization slag in the neutralization process. The slag's main components are calcium sulfate, metal hydroxides, and silicon dioxide. This neutralization slag is not currently being effectively utilized and is simply piled up in waste dumps, wasting significant land resources and posing potential environmental pollution risks. Therefore, the effective disposal and utilization of neutralization slag is an urgent problem to be solved.

[0004] Expanded clay aggregate (ECA) is a lightweight aggregate that can be used as a base material in building materials, for producing lightweight wall panels, self-insulating EC blocks, or as a substitute for sand and gravel as coarse aggregate in concrete. Currently, the production of EC from gold tailings often involves a sintering process. Sintering not only wastes energy and pollutes the environment, but also often requires large-scale sintering equipment, increasing production costs.

[0005] In view of this, it is necessary to design an improved non-fired ceramsite for gold tailings and its preparation method to solve the above problems. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a non-fired ceramsite for gold tailings and its preparation method. By rationally designing parameters such as raw material ratio and curing conditions, the invention achieves the goal of non-fired ceramsite preparation from gold tailings, which can create good economic, environmental and social benefits.

[0007] To achieve the above objectives, the present invention provides a method for preparing non-fired ceramsite from gold tailings, comprising the following steps:

[0008] S1. Gold tailings, cement, and neutralization slag are mixed with hydrogen peroxide solution according to a predetermined mass ratio to prepare a mixture containing spherical cores;

[0009] S2. Transfer the mixture containing the cores described in step S1 into a pelletizing device, add hydrogen peroxide solution to pelletize, sieve the pellets, and select pellets with a diameter of 10-20 mm and a moisture content of 20-30% as wet raw pellets.

[0010] S3. Place the wet raw material balls described in step S2 into a steam curing kiln for curing to obtain gold tailings non-fired ceramsite.

[0011] As a further improvement of the present invention, in step S1, the predetermined mass ratio is 50-80% gold tailings, 10-30% cement and 10-20% neutralization slag, and the concentration of the hydrogen peroxide solution is 2.5-7.5%.

[0012] Furthermore, the gold tailings contain a total of more than 70% silica and more than 55% alumina. The neutralization slag is a neutralization slag from the treatment of acidic mine wastewater, containing less than 20% silica, more than 60% calcium sulfate, and more than 15% alkali metals and hydroxides. The cement is ordinary Portland cement with a strength of 42.5 MPa or higher.

[0013] As a further improvement of the present invention, the proportion of gold tailings with a mesh size of 200 mesh is more than 80%, and the proportion of neutralization slag with a mesh size of 200 mesh is more than 90%.

[0014] The moisture content of the mixture containing the core is 1 / 3 to 1 / 2 of the moisture content of the wet raw material balls.

[0015] As a further improvement of the present invention, in step S2, the concentration of the hydrogen peroxide aqueous solution is 2.5% to 7.5%.

[0016] As a further improvement of the present invention, in step S3, the curing method is to cure in steam at 80-100°C for 8-12 hours.

[0017] The present invention also provides a gold tailings non-fired ceramsite, which is prepared by the above-mentioned method for preparing gold tailings non-fired ceramsite.

[0018] The beneficial effects of this invention are:

[0019] 1. The gold tailings non-fired ceramsite and its preparation method provided by the present invention, through reasonable control of the raw material ratio for preparation and curing, stabilizes and immobilizes pollutants such as cyanide and COD in the gold tailings, so that the resulting ceramsite product meets the relevant environmental protection requirements of the "Technical Guidelines for Pollution Prevention and Control of Solid Waste Recycling" (HJ 1091-2020), and realizes the harmless resource utilization of solid wastes such as gold tailings and neutralization slag.

[0020] 2. The gold tailings non-fired ceramsite and its preparation method provided by this invention make full use of the calcium sulfate contained in the neutralization slag, which acts as a good binder in the granulation stage and can significantly improve the strength of the raw material pellets. At the same time, the neutralization slag acts as an alkali activator, which can enable the gold tailings and cement to react fully during the oxidation process. During the steam curing process, hydrogen peroxide is heated and decomposed to generate oxygen gas which is fixed in the matrix. Finally, after curing, porous non-fired ceramsite is formed. This method has the advantages of high preparation efficiency, low energy consumption, low carbon emissions, low cost, and excellent ceramsite performance (low water absorption and low bulk density).

[0021] 3. The gold tailings non-fired ceramsite and its preparation method provided by this invention, taking into account the resource occurrence characteristics of gold tailings and neutralization slag, and combining current ceramsite production technology, utilizes rationally designed process parameters such as material ratios to sequentially process gold tailings and neutralization slag through material preparation, pelletizing and screening, and curing processes, thereby achieving the resource utilization of solid waste. Based on the above approach, the method provided by this invention can improve the comprehensive utilization rate of solid waste and reduce the environmental pollution risks caused by its stockpiling.

[0022] 4. The preparation method of gold tailings non-fired ceramsite provided by the present invention is simple, safe and reliable in operation, and has no secondary pollution. It can realize the resource utilization of bulk solid waste, and has significant economic, environmental and social benefits, providing a new idea for the comprehensive utilization of mine solid waste. Attached Figure Description

[0023] Figure 1 The process flow diagram of the preparation method of gold tailings non-fired ceramsite provided by the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0026] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0027] This invention provides a method for preparing non-fired ceramsite from gold tailings, such as... Figure 1 As shown, it includes the following steps:

[0028] S1. Gold tailings, cement, and neutralization slag are mixed with hydrogen peroxide solution according to a predetermined mass ratio to prepare a mixture containing spherical cores.

[0029] Specifically, according to the mass percentage, 50-80% of gold tailings, 10-30% of cement, and 10-20% of neutralization slag are transferred into a pre-wetting mixer for mixing. During the mixing process, a hydrogen peroxide solution with a volume percentage of 2.5-7.5% is added to the pre-wetting mixer to obtain a wet material with a moisture content of 1 / 3 to 1 / 2 of that of the wet raw material pellets. The wet material is then mixed to obtain a mixture containing pellet cores.

[0030] In the above steps, the gold tailings (-200 mesh) account for more than 80%, and the combined content of silica and alumina in the gold tailings is greater than 70%, with a silica content greater than 55%. The neutralization slag is from the treatment of acidic mine wastewater, with a -200 mesh content of more than 90%, a silica content of less than 20%, a calcium sulfate content greater than 60%, and a combined alkali metal and hydroxide content greater than 15%. The cement used is ordinary Portland cement with a strength of 42.5 MPa or higher.

[0031] S2. Transfer the mixture containing the core from step S1 into a pelletizing device, add hydrogen peroxide solution to pelletize, sieve the pellets, and select pellets with a diameter of 10-20 mm and a moisture content of 20-30% as wet raw pellets.

[0032] Specifically, the mixture from step S1 is transferred into a pelletizing device. During the rolling process of the mixture, a hydrogen peroxide solution with a volume percentage of 2.5% to 7.5% is added to control the moisture content of the pellets prepared by rolling to 20% to 30%. Then, the pellets are screened to select pellets with a diameter of 10 to 20 mm as wet raw pellets.

[0033] S3. Place the wet raw material balls from step S2 into a steam curing kiln for curing to obtain gold tailings non-fired ceramsite.

[0034] Specifically, the wet raw material pellets prepared in step S2 are transferred to a steam curing kiln for curing, and cured in steam at 80-100℃ for 8-12 hours to obtain gold tailings non-fired ceramsite.

[0035] The following describes the gold tailings non-fired ceramsite and its preparation method provided by the present invention with reference to specific embodiments.

[0036] Example 1

[0037] Example 1 provides a method for preparing non-fired ceramsite from gold tailings, comprising the following steps:

[0038] S1. Transfer 50 parts of gold tailings, 30 parts of cement and 20 parts of neutralization slag into a pre-wetted mixer for mixing, and add 5% hydrogen peroxide solution by volume into the mixer to prepare a mixture containing spherical cores with a water content of 10-15%.

[0039] S2. Transfer the mixture from step S1 into a disc pelletizer. During the rolling process of the mixture, continue to add a certain amount of hydrogen peroxide solution with a volume percentage of 5% to form pellets. Screen the pellets and select pellets with a diameter of 10-20 mm and a moisture content of 20% as wet raw pellets.

[0040] S3. Transfer the wet raw material pellets prepared in step S2 to a steam curing kiln for curing. Curing in steam at 80°C for 12 hours yields gold tailings non-fired ceramsite.

[0041] Example 2

[0042] Example 2 provides a method for preparing non-fired ceramsite from gold tailings, comprising the following steps:

[0043] S1. Transfer 60 parts of gold tailings, 25 parts of cement and 15 parts of neutralization slag into a pre-wetted mixer for mixing, and add 4% hydrogen peroxide solution by volume into the mixer to prepare a mixture containing spherical cores with a water content of 10-15%.

[0044] S2. Transfer the mixture from step S1 into a disc pelletizer. During the rolling process of the mixture, continue to add a certain amount of hydrogen peroxide solution with a volume percentage of 4% to form pellets. Screen the pellets and select pellets with a diameter of 10-20 mm and a moisture content of 20% as wet raw pellets.

[0045] S3. Transfer the wet raw material pellets prepared in step S2 to a steam curing kiln for curing. Curing in steam at 90°C for 10 hours yields gold tailings non-fired ceramsite.

[0046] Example 3

[0047] Example 3 provides a method for preparing non-fired ceramsite from gold tailings, comprising the following steps:

[0048] S1. Transfer 80 parts of gold tailings, 10 parts of cement and 10 parts of neutralization slag into a pre-wetted mixer for mixing, and add 2.5% hydrogen peroxide solution by volume into the mixer to prepare a mixture containing spherical cores with a water content of 10-15%.

[0049] S2. Transfer the mixture from step S1 into a disc pelletizer. During the rolling process of the mixture, continue to add a certain amount of hydrogen peroxide solution with a volume percentage of 2.5% to form pellets. Screen the pellets and select pellets with a diameter of 10-20 mm and a moisture content of 20% as wet raw pellets.

[0050] S3. Transfer the wet raw material pellets prepared in step S2 to a steam curing kiln for curing. Curing in steam at 100°C for 8 hours yields gold tailings non-fired ceramsite.

[0051] Comparative Examples 1-3

[0052] Comparative Examples 1-3 each provide a method for preparing non-fired ceramsite from gold tailings. Compared with Example 1, the only difference is the mass fraction of gold tailings, cement, and neutralization slag. Comparative Example 1 uses 100% gold tailings, Comparative Example 2 uses 70% gold tailings and 30% neutralization slag, and Comparative Example 3 uses 60% gold tailings, 30% neutralization slag, and 10% cement. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0053] Comparative Examples 4-6

[0054] Comparative Examples 4-6 provide a method for preparing non-fired ceramsite from gold tailings. Compared with Example 1, the only difference is that the concentration of hydrogen peroxide solution in Comparative Example 4 is 1%, the curing time in Comparative Example 5 is 6 hours, and the curing temperature in Comparative Example 6 is 70°C. Other experimental parameters and conditions are basically the same as those in Example 1, and will not be repeated here.

[0055] The main components of the gold tailings and neutralization slag in the embodiments and comparative examples of this invention are detailed in Tables 1 and 2, wherein the gold tailings (-200 mesh) account for more than 85%, the neutralization slag (-200 mesh) from the treatment of acidic mine wastewater accounts for more than 90%, and the key process parameters for preparation are detailed in Table 3.

[0056] Table 1 Composition of Gold Tailings Raw Materials

[0057] content(%) 0.11 0.01 0.05 2.63 0.04 0.07 0.19 0.31 element Ca Mg Si Al O K Na F content(%) 1.36 0.14 49.39 3.66 38.11 2.63 1.08 0.02

[0058] Table 2 shows the composition of the neutralization slag raw materials.

[0059] content(%) 62 18 20

[0060] Table 3 Key process parameters for the preparation of expanded clay aggregate

[0061]

[0062] The performance of the gold tailings non-fired ceramsite prepared in Examples 1-3 and Comparative Examples 1-6 was tested, and the results are shown in Table 4.

[0063] Table 4 Properties of Ceramsite

[0064]

[0065] Table 4 shows that in Examples 1-3, the ceramsite prepared using the method of this invention has low water absorption, low bulk density, and high compressive strength. Furthermore, as the amount of hydrogen peroxide added increases, the bulk density gradually decreases, but the compressive strength is not significantly affected, meeting the performance requirements for ceramsite with a density of 400-600. Within the conditions of the examples, longer curing time and higher temperature are more beneficial to the quality of the ceramsite. In Comparative Examples 1-3, as the amount of tailings added increases, the apparent density and bulk density gradually increase, far exceeding the density requirements of lightweight aggregates. Simultaneously, as the amount of cement added decreases, the compressive strength of the ceramsite gradually decreases, failing to meet the relevant product quality requirements. In Comparative Examples 4-6, hydrogen peroxide and curing temperature have a significant impact on the apparent density and bulk density of the ceramsite. Lower hydrogen peroxide dosage and lower curing temperature result in higher ceramsite density, while shorter curing time leads to lower compressive strength.

[0066] The concentration of leached heavy metals in the ceramsite prepared by this invention was tested, and the specific results are shown in Table 5.

[0067] Table 5. Limits for heavy metal content that can be leached from expanded clay aggregate.

[0068]

[0069] Note: Unless otherwise noted, the units for the indicators in the table are ug / L.

[0070] As shown in Table 5, the heavy metal concentration in the leachate of the ceramsite prepared in Examples 1-3 is far lower than the heavy metal concentration limit in the leachate specified in the Technical Guidelines for Pollution Prevention and Control of Solid Waste Recycling (HJ 1091-2020).

[0071] In summary, the gold tailings non-fired ceramsite and its preparation method provided by this invention use gold tailings as the main raw material, combined with neutralized slag from acidic mine wastewater as a binder and activator, and hydrogen peroxide as a foaming agent. Through granulation, curing and other processes, the ceramsite produced from solid waste has excellent performance, with the advantages of high preparation efficiency and low cost. It realizes the full resource utilization of gold tailings and neutralized slag from acidic mine wastewater treatment, and has good economic, environmental and social benefits.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing non-fired ceramsite from gold tailings, characterized in that, Includes the following steps: S1. Gold tailings, cement, and neutralization slag are mixed with hydrogen peroxide solution according to a predetermined mass ratio to prepare a mixture containing spherical cores; The predetermined mass ratio is 50-80% gold tailings, 10-30% cement, and 10-20% neutralization slag; the concentration of the hydrogen peroxide solution is 2.5-7.5%. The gold tailings contain a total of more than 70% silica and more than 55% alumina. The neutralization residue is a neutralization residue for the treatment of acidic mine wastewater. The neutralization residue contains less than 20% silica, more than 60% calcium sulfate, and more than 15% alkali metals and hydroxides. The gold tailings with a mesh size of -200 mesh account for more than 80%, and the neutralization slag with a mesh size of -200 mesh account for more than 90%. S2. Transfer the mixture containing the cores described in step S1 into a pelletizing device, add hydrogen peroxide solution to pelletize, sieve the pellets, and select pellets with a diameter of 10-20 mm and a moisture content of 20-30% as wet raw pellets; the concentration of the hydrogen peroxide solution is 2.5-7.5%; S3. Place the wet raw material balls described in step S2 into a steam curing kiln for curing to obtain gold tailings non-fired ceramsite. The curing method involves curing in steam at 80-100℃ for 8-12 hours.

2. The method for preparing non-fired ceramsite from gold tailings according to claim 1, characterized in that, The cement is ordinary Portland cement with a strength of 42.5 MPa or higher.

3. The method for preparing non-fired ceramsite from gold tailings according to claim 1, characterized in that, In step S1, the moisture content of the mixture containing the core is 1 / 3 to 1 / 2 of the moisture content of the wet raw material balls.

4. A type of non-fired ceramsite for gold tailings, characterized in that, It is prepared by the method for preparing non-fired ceramsite of gold tailings as described in any one of claims 1-3.

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