Preparation method and application of silver tailings slag composite material

Abstract

The application discloses a preparation method and application of a silver tailing slag composite material, and relates to the technical field of cement production, and particularly relates to a preparation method of a silver tailing slag composite material. The preparation method comprises the following steps: drying and carbonizing silver tailing slag, mixing the silver tailing slag with iron slag powder and fly ash, adding YT and YTM additives, and then grinding; and the application of the silver tailing slag composite material in cement production can keep the early strength of the cement basically unchanged, can slightly increase the late strength of the cement, and can meet the quality index requirements of other indexes. Due to the mixing of the fine particles, the durability, the frost resistance and the permeability resistance of the cement can be improved. The above test shows that the composite additive can be applied in the cement production.

Description

Technical Field

[0001] This invention relates to the field of tailings treatment, and in particular to a method for treating silver tailings slag and its application. Background Technology

[0002] Tailings are components generated during mineral processing with low levels of useful elements that are currently uneconomical for industrial production. They are also a major component of industrial solid waste. Currently, large quantities of tailings are stored in tailings ponds as "solid waste." Ignoring these tailings ponds poses a potential threat to the balance of the natural ecosystem and public safety.

[0003] The key to realizing the resource utilization of tailings lies in using existing technologies and processes to maximize the application of elements in tailings as raw materials in various fields, without wasting resources or polluting the environment.

[0004] Currently, the utilization rate of existing silver tailings in my country is only about 18%, and the utilization rate of newly added tailings is about 25% (cited from an article by Koala Ecological Development on March 4, 2022). A large amount of tailings is piled up in tailings ponds. How to achieve the resource utilization of tailings discharged after silver ore flotation is a goal pursued by those skilled in the art. Among these, the treatment of silver tailings is particularly difficult, and currently there are no effective methods for resource utilization. Summary of the Invention

[0005] The inventors conducted tests on the silver tailings. The silver tailings are lead, zinc, and silver veins formed by low-temperature hydrothermal fluids from a volcano. The main minerals contained in the tailings are crystalline SiO2 and some potassium feldspar minerals. The chemical composition is shown in Appendix 1.

[0006]

[0007] Table 1. Analysis results of main chemical components

[0008] Research has found that, under existing technological utilization schemes, silver tailings can be used as raw material in the cement and building materials industry as a silica correction material. However, due to the high-temperature decomposition of potassium feldspar producing alkaline oxide K2O, the K2O in the cement raw meal can easily cause scaling and blockage in the kiln tail preheater during calcination, which has an adverse effect on production; therefore, it cannot be used in large quantities.

[0009] The purpose of this invention is to provide a method for preparing silver tailings slag composite materials; the specific technical solution is as follows:

[0010] Includes the following steps:

[0011] 1) Drying: The moisture content of silver tailings slag after filter pressing is 20.0~23.0%, and it needs to be dried in a dryer until the moisture content is less than 1.0%;

[0012] 2) Carbonization: Add 5-10% quicklime powder to the dried silver tailings, mix thoroughly, put into a carbonization tank, and introduce the flue gas from the drying fluidized bed furnace; use the residual heat generated by the drying fluidized bed furnace and CO2 and CO in the flue gas to carbonize the silver tailings for 5-6 hours.

[0013] 3) Mixing: Cool to below 90℃, mix with iron slag powder and fly ash in a mass ratio of 30~40:30~40:40~20 to form a mixture, and then mix with 1-2% YTM additive;

[0014] 4) Grinding: Place in a ball mill for grinding; add 0.1% YT additive at the feed end of the mill to achieve a specific surface area of ​​600m². 2 Amounts of / kg or more were discharged from the mill; silver tailings slag composite material was obtained.

[0015] Furthermore, the YT additive comprises the following mass percentages: 20-25% naphthalene sulfonate formaldehyde condensate, 8-10% triethanolamine, 6-12% glycerol, 8-12% ethylene glycol, 3-5% polyacrylamide, and the balance being purified water.

[0016] Furthermore, the YTM additive is prepared from water glass, gypsum, calcined lime, and sodium sulfate in a mass ratio of 1:2-5:2.5-5:5-10.

[0017] The present invention also discloses the application of the above-mentioned silver tailings slag composite material. When the silver tailings slag composite material is applied to cement, the mass percentage of the silver tailings slag composite material in the raw materials of the cement is not greater than 50%.

[0018] The preparation method of the silver tailings slag composite material of this invention involves drying and carbonizing the silver tailings slag, mixing it with iron slag powder and fly ash, adding YT and YTM additives, and then grinding it. When applied to cement, the early strength of the cement remains basically unchanged, and the later strength shows only slight increase. Other indicators also meet the quality requirements. Due to the incorporation of fine particles, the durability, frost resistance, and impermeability of the cement are improved. The above experiments show that this composite admixture can be used in cement production for resource utilization. Detailed Implementation

[0019] The invention will now be described more fully by way of examples. The invention can be embodied in many different forms and should not be construed as being limited to the exemplary embodiments described herein. Example 1

[0020] First, prepare dry powder of silver tailings slag:

[0021] Drying: A φ3.6×9M three-cylinder dryer is used to achieve the drying and carbonization of silver tailings slag during the drying process. Carbonization treatment: 90~95% silver tailings slag + 5~10% quicklime are mixed evenly and fed into the dryer for drying. The furnace temperature is controlled at 800℃~950℃. The flue gas enters the dust collector, and the material in the dust collector and the material from the dryer are sent to the storage tank. Some high-temperature flue gas is introduced from the furnace into the tank, and the temperature is controlled at 300℃~450℃. While drying and carbonization are carried out simultaneously, the moisture content of the silver tailings slag should be controlled below 1%. The dried silver tailings slag material is kept in a 600-ton capacity storage tank for 3-6 hours to slowly cool to below 90℃, and then it can be ground together with fly ash and iron slag powder.

[0022] Silver tailings slag that has been dried and carbonized for more than 6 hours, iron slag powder, and fly ash are weighed and batched at a weight ratio of 30:40:30 using a weighing scale at the bottom of the silo, and then fed into a φ2.6×13m ball mill for grinding. During this process, the specific surface area of ​​the material exiting the mill is required to reach 600 m². 2 For samples weighing / kg or above, the specific quality indicators should comply with (T / CBMF194—2022); as shown in Table 2.

[0023]

[0024] Table 2 Requirements for Powder Quality Indicators

[0025] To achieve the above quality indicators, two additives were added to the ingredients: one is YT additive, which has water-reducing, antistatic, and activating effects; the YT additive composition is: 25% naphthalene sulfonate formaldehyde condensate, 10% triethanolamine, 8% glycerol, 10% ethylene glycol, 5% polyacrylamide, and the balance is purified water. The amount added during grinding of the silver tailings slag composite material is 0.1% of the composite material's mass. The other additive is YTM additive: prepared from water glass, gypsum, calcined lime, and sodium sulfate in a mass ratio of 1:5:5:10. The amount added during grinding of the silver tailings slag composite material is 1.0~2.0% of the composite material's mass, and it is added using a batching scale.

[0026] The composite powder, prepared by mixing dried and carbonized silver tailings slag, iron slag powder, and fly ash in the above proportions with additives, and then processing it using a ball mill, was tested. The results of various performance parameters are shown in Table 3.

[0027]

[0028] Table 3 Quality Indicators of Composite Powder

[0029] As can be seen from the data in Table 3, the performance indicators of the silver tailings slag composite material obtained by Step 1 and Step 2 meet the standard requirements and can meet the technical requirements of cement and concrete admixtures, and can be used.

[0030] A comparative experiment was conducted in a laboratory to compare the silver tailings composite admixture obtained in steps one and two with silver tailings slag powder. First, the silver tailings slag powder was dried, and the moisture content was determined to be 0.9%. Then, 5 kg of the sample was placed in a φ500×500 test mill and ground for 10 minutes, resulting in a specific surface area of ​​680 m². 2 / kg, using Po 42.5 ordinary Portland cement as the test sample for testing. Test sample mix ratio:

[0031] Cement: Silver tailings slag powder: 50:50

[0032] Cement: Silver tailings slag composite admixture: 50:50

[0033] The cement physical testing standards were followed, and the results are shown in Table 4.

[0034]

[0035] Table 4

[0036] Comparative tests show that the original silver tailings slag is inactive, but after carbonization, composite grinding and chemical activation, it has good activity and can be made into active cement and concrete admixtures, which are widely used in the building materials and construction fields. Example 2

[0037] Silver tailings slag mixed with 5% quicklime was fed into a φ3.6×9m three-cylinder dryer. The combustion temperature in the dryer furnace was controlled at 800℃-950℃. A portion of the high-temperature gas was directly fed into a storage tank, where the temperature was controlled at 450℃-500℃. This temperature was maintained for at least 4-8 hours until the moisture content was less than 1.0%. The dried dust and the material exiting the dryer were simultaneously fed into a 600-ton storage tank. The dryer operated for two shifts, totaling 16 hours. 320 tons of silver tailings slag mixed with quicklime were dried. After a 24-hour drying stop, the slag was ground. The mixing ratio of silver tailings slag, iron slag powder, and fly ash was 30:30:40. The mixture was weighed using a spiral metering system at the bottom of the silo and fed into a φ2.6×13m ball mill for grinding. The finished product was sent to the finished product silo #1. Grinding lasted 8 hours, producing 240 tons. Samples were taken hourly to maintain a specific surface area of ​​650 m². 2 For powders weighing above / kg and with a 0.032μm square hole sieve sieve size ≤2.0, the two additives described in step two are added during the grinding process.

[0038] The samples were allowed to cool to room temperature before undergoing physical testing in the laboratory to confirm their activity. The cement sample used in the test was Po 42.5 ordinary Portland cement. The test results are shown in Table 5.

[0039]

[0040] Table 5

[0041] As can be seen from the table above, the composite admixture obtained from this experiment, which is jointly ground from silver tailings slag, iron slag powder, and fly ash, has an activity of 75.2% after seven days and 97% after twenty-eight days, meeting the technical index requirements of national standards. It can be used as a production solution to address the problem of silver tailings accumulation. Example 3

[0042] The process was essentially the same as in Example 2, except that a composite admixture prepared by mixing silver tailings powder, iron slag powder, and fly ash in a ratio of 30:30:40 was sent to the storage tank at the tail end of the φ3.8×13m production line at the SXSG cement plant. The mill operated for 8 hours, with an hourly output of 120 tons / hour, producing PSA 32.5 grade cement. 15% of the silver tailings powder composite admixture was added to the air chute at the tail end of the mill. A total of 952 tons of cement were produced during this shift. Samples were taken once per hour before and after the admixture was added, for a total of eight samplings. The samples taken before and after the admixture were then mixed separately and subjected to physical testing and comparison in the laboratory. The test results for the samples before and after the admixture are shown in Table 6 below.

[0043]

[0044] Table 6

[0045] When 15% silver tailings slag powder is added to 32.5 slag cement, the initial strength of the cement remains basically unchanged, and the later strength shows only a slight increase. Other indicators also meet the quality requirements. Due to the addition of fine particles, the durability, frost resistance, and impermeability of the cement are improved. The above experiments show that this composite admixture can be applied in cement production through resource utilization.

[0046] The above examples are only for illustrating the present invention. In addition, there are many other different implementations, which can be conceived by those skilled in the art after understanding the concept of the present invention. Therefore, they will not be listed one by one here.

Claims

1. A method for preparing a silver tailings slag composite material, characterized in that, Includes the following steps: 1) Drying: The moisture content of silver tailings slag after filter pressing is 20.0~23.0%, and it needs to be dried in a dryer until the moisture content is less than 1.0%; 2) Carbonization: Add 5-10% quicklime powder to the dried silver tailings, mix thoroughly, put into a carbonization tank, and introduce the flue gas from the drying fluidized bed furnace; use the CO2 in the flue gas generated by the drying fluidized bed furnace to carbonize the silver tailings for 5-6 hours. 3) Mixing: Cool the product from step 2) to below 90°C, and mix it with iron slag powder and fly ash in a mass ratio of 30~40:30~40:40~20 to form a mixture; add 1-2% YTM additive and mix. The YTM additive is prepared by mixing water glass, gypsum, calcined lime, and sodium sulfate in a mass ratio of 1:2-5:2.5-5:5-10. 4) Grinding: Place in a ball mill for grinding; add 0.1% YT additive at the feed end of the mill to achieve a specific surface area of ​​600m². 2 / kg or more of the material is discharged from the mill; silver tailings slag composite material is obtained; the mass percentage of the raw materials in the YT additive is: 25% naphthalene sulfonate formaldehyde condensate, 10% triethanolamine, 8% glycerol, 10% ethylene glycol, 5% polyacrylamide, and the balance is purified water.

2. An application of a silver tailings slag composite material, characterized in that, When applied to cement, the mass percentage of the silver tailings slag composite material prepared by the preparation method as described in claim 1 in the raw materials of the cement is not greater than 50%.

Images