Method for solidifying copper tailing waste through magnesium oxychloride cement

Abstract

The invention provides a method for solidifying copper tailing waste by magnesium oxychloride cement, which comprises the following steps: dissolving carbonic anhydrase in water, mixing with copper tailings, magnesium oxychloride cement, metakaolin and clay, carrying out microwave treatment and dry mixing on the mixture, then adding water, and continuously stirring uniformly to obtain cement slurry; the curing method comprises the steps that cement slurry is injected into a mold or a mine pit and cured after being vibrated and compacted, a direct-current electric field is continuously applied to the slurry in the curing process, carbon dioxide curing and natural curing are intermittently conducted, and the cement component is obtained after curing is completed. The magnesium oxychloride copper tailing cement prepared by the invention can be used as a road base material or a mine backfill material. The magnesium oxychloride cement is used for curing the copper tailing waste, the prepared cement component is high in strength, excellent in water resistance and low in heavy metal leaching toxicity, the engineering requirements of road base laying or pit backfilling and the like can be fully met, and a new way is opened up for harmless treatment and sustainable utilization of the copper tailings.

Description

Technical field:

[0001] The invention belongs to the technical field of solid waste treatment, and particularly relates to a method for solidifying copper tailings waste by using magnesium oxychloride cement. Background technology:

[0002] Copper tailings are solid waste generated during copper mining and beneficiation. The annual discharge is large, and its complex physical and chemical properties make large-scale disposal face severe challenges. Taking the Daye copper tailings in Hubei as an example, XRD analysis shows that its main phases are quartz (52.3%-58.7% SiO2), feldspar (11.4%-16.2% Al2O3) and hematite (7.8%-13.5% Fe2O3), and trace heavy metals (0.04%-0.19% Cu, 0.12%-0.47% Zn, 0.07%-0.23% Pb, 0.03%-0.09% As). Heavy metal ions (such as Cu 2+ ) is concentrated in fine particles with a particle size of <75 μm and has an enrichment rate of more than 80%. It is easily migrated through rainwater leaching and has a great impact on the Cu 2+ Leaching concentrations can reach 4.7-15.3 mg / L. If improperly handled, these heavy metal ions can leach into water systems and soil through rainwater, causing environmental pollution and posing a potential threat to ecosystems and human health. Therefore, the safe treatment and resource utilization of copper tailings are key issues in mine environmental remediation projects.

[0003] Existing copper tailings disposal technologies mainly include resource recovery, cement solidification, and the preparation of geopolymers, but all have significant drawbacks. Patent CN118904525A discloses a beneficiation method for recovering copper from copper tailings. Although this copper tailings resource recovery technology can reduce the copper content of the tailings, it has high reagent costs, complex processes, high requirements for the properties of the tailings, limited recovery rate improvement, high processing costs, and is prone to secondary pollution. Patent CN116161885A discloses a method for preparing silicate cement using copper tailings, but its calcination temperature is as high as 1350-1450°C, which consumes a lot of energy and has high carbon emissions, causing a large greenhouse gas pressure on the environment. The solidification effect on heavy metals is mainly physical adsorption, and the durability of the silicate cement solid body is poor. Under the influence of long-term natural environment, the solid body may gradually crack or even disintegrate due to its low strength and high porosity, resulting in the re-release of heavy metal ions into the environment, thereby increasing the risk of secondary leaching of heavy metal ions. In addition, although magnesium phosphate cement curing technology has the characteristics of fast setting and high strength, it uses a large amount of sintered magnesium oxide calcined at 1600-1800℃, which is high in cost and energy consumption. 2+ The stabilization effect after plasma curing is still not ideal, Cu 2+Therefore, the present invention proposes a method for solidifying copper tailings waste by using magnesium oxychloride cement to solve the above problem. Summary of the invention:

[0004] The purpose of the present invention is to provide a method for solidifying copper tailings waste with magnesium oxychloride cement in view of the shortcomings of the prior art. Based on the solidification process of magnesium oxychloride cement, the carbon emission is reduced by more than 60% through high dosage design (adding 30%-50% copper tailings) and low temperature solidification characteristics. At the same time, the Mg in 5MgO·MgCl2·8H2O (5·1·8) is used to solidify the copper tailings waste. 2+ Ions can react chemically with copper ions to form stable compounds or complexes, thereby fixing copper ions in the crystal structure and making Cu 2+ Leaching concentration <2.0mg / L.

[0005] The present invention adopts the following technical solutions:

[0006] The invention provides a method for solidifying copper tailings waste by using magnesium oxychloride cement. The method comprises the following steps: dissolving carbonic anhydrase in water, mixing the mixture with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subjecting the mixture to microwave treatment, dry mixing after the microwave treatment, adding water and continuing to stir evenly to obtain magnesium oxychloride copper tailings cement.

[0007] Furthermore, the weight ratio of the copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:25-200:0.01-0.1:2.5-20:5-15:50-150.

[0008] Furthermore, the magnesium oxychloride cement is prepared by mixing light-burned magnesium oxide, magnesium chloride and organic acid; the weight ratio of the light-burned magnesium oxide, magnesium chloride and organic acid is 1.0:0.5-2.0:0.002-0.01.

[0009] Furthermore, the organic acid is apple cider vinegar, which has an acetic acid content of 4% to 6% and a pH value of 2.5 to 3.5.

[0010] Furthermore, the magnesium chloride is a mixture of one or more of magnesium chloride dihydrate, magnesium chloride tetrahydrate and magnesium chloride hexahydrate; the light-burned magnesium oxide is a product of magnesite calcined at 750-1000° C., wherein the active magnesium oxide content is 45%-80%; or the light-burned magnesium oxide is a product of dolomite calcined at 650-780° C., wherein the active magnesium oxide content is 18%-30%.

[0011] Furthermore, the copper tailings include 10%-40% SiO2, 5%-20% Fe2O3, 5%-15% CaO, 5%-15% Al2O3, 1%-10% MgO, 0.1%-5% CuO and 0.1%-3% ZnO.

[0012] Furthermore, the specific surface area of the metakaolin is greater than 300-500m 2 / kg, an activity index greater than 70%; the particle size of the clay is no greater than 5mm, and the moisture content is 1%-15%.

[0013] Furthermore, the microwave power is 300-600W, the microwave treatment time is 3-5 minutes, and the dry mixing time is 1-3 minutes.

[0014] Furthermore, it also includes a curing operation, specifically: injecting the evenly mixed magnesium oxychloride copper tailings cement into a mold or a mine pit, vibrating and compacting it, and then curing it. During the curing process, a DC electric field is continuously applied to the slurry. The curing process includes carbon dioxide curing and natural curing, and the carbon dioxide curing and natural curing are performed intermittently. After the curing is completed, the magnesium oxychloride copper tailings cement component is obtained.

[0015] Furthermore, the carbon dioxide curing is carried out on the 3rd to 5th day of curing, with 2 to 3 periods selected each day, each period lasting 1 to 2 hours, and the solidified body is placed in a carbon dioxide environment with a carbon dioxide concentration of 10% to 20%; the natural curing is carried out outside the carbon dioxide curing period, and the solidified body is covered with straw bags or films to avoid exposure to the sun.

[0016] Furthermore, the DC electric field is 5-15 V / cm.

[0017] Furthermore, spectral analysis technology is used to monitor the curing process in real time during the curing period, and stress and strain changes are monitored through stress and strain sensors in the mold or pit. When the threshold is exceeded, automatic adjustment is performed. The curing time is at least 7 days. After the specified time is reached, the mold is removed to obtain a cured specimen.

[0018] Furthermore, the prepared copper tailings magnesium oxychloride cement components are used as road base materials or mine backfill materials.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement to prepare magnesium oxychloride copper tailings cement. Compared with traditional solidification materials, the process of solidifying copper tailings waste using magnesium oxychloride cement of the present invention has significant economic advantages. The production process of magnesium oxychloride cement has low energy consumption and low cost, and the raw materials are widely available, which can effectively reduce the economic burden of solidification treatment and provide economic feasibility for large-scale industrial application.

[0021] (2) The magnesium oxychloride cement of the present invention exhibits remarkable stability in solidifying heavy metal ions. Unlike traditional cement that mainly relies on physical adsorption, 5MgO·MgCl2·8H2O (5·1·8) in magnesium oxychloride cement acts through multiple mechanisms such as physical adsorption and chemical bonding to fix copper ions in the crystal structure, achieving efficient solidification of heavy metal ions and forming copper-containing hydration products, thereby constructing a stable solidification system. This multi-mechanism synergistic effect makes the solidified body excellent in terms of leaching toxicity, and the leaching rate of heavy metal ions is much lower than that of traditional cement solidified bodies, effectively reducing the potential pollution risk to the environment;

[0022] (3) The process flow for curing copper tailings with magnesium oxychloride cement is simple, and no additional watering or curing is required. Ideal curing effects can be achieved through natural curing alone. This feature not only reduces the complexity of construction operations but also reduces water consumption, further enhancing the environmental friendliness of the process.

[0023] (4) The present invention can achieve solidification treatment of copper tailings under a variety of complex working conditions, including open-pit, mine, underground, and underwater environments. This wide applicability enables magnesium oxychloride cement solidification technology to be effective in different scenarios, providing a flexible solution for resource utilization and environmental remediation of copper tailings. Description of the drawings:

[0024] Figure 1 This is a process flow chart of the present invention for solidifying copper tailings waste using magnesium oxychloride cement;

[0025] Figure 2 This is a graph showing the change in copper ion leaching concentration over time in the solidified bodies obtained in Comparative Example 1 and Examples 1-4;

[0026] Figure 3 Mg 2+ With Cu 2+ Schematic diagram of complex formation. Specific implementation method:

[0027] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts are within the scope of protection of this application.

[0028] Example 1

[0029] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0030] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 750° C., with an active magnesia content of 45%), 0.5 part of magnesium chloride (magnesium chloride dihydrate), and 0.002 part of apple vinegar (acetic acid content of 4%, pH value of 2.5) to obtain magnesium oxychloride cement.

[0031] Step 2: Pre-dissolve carbonic anhydrase with a portion of water, then mix with copper tailings, magnesium oxychloride cement, metakaolin (specific surface area 300m 2 / kg, activity index 70%) and clay (clay particle size not greater than 5mm, moisture content 1%) are mixed to obtain a mixture; the mixture is subjected to microwave treatment, the microwave power is set to 400W, and the treatment is carried out for 3 minutes. After the microwave treatment is completed, the mixture is transferred to a stirring device for dry mixing, dry mixing for 3 minutes, and then another portion of water is added and continued to be stirred until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:25:0.01:2.5:5:50.

[0032] Step 3: Pour the slurry mixed in step 2 into a mold or a mine pit, vibrate and compact it, and then cure it for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry.

[0033] The curing process includes both CO2 curing and natural curing. CO2 curing is performed on days 3 to 5 of curing, with three 2-hour periods each day. The cured specimen is placed in a CO2 environment with a CO2 concentration of 20%. Natural curing occurs outside of the CO2 curing period, with the cured specimen covered with straw bags or film to protect it from direct sunlight. After the 7-day curing period, the mold is removed to obtain the cured specimen.

[0034] Example 2

[0035] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0036] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 750° C., with an active magnesia content of 45%), 1.0 part of magnesium chloride (magnesium chloride tetrahydrate), and 0.004 part of apple vinegar to obtain magnesium oxychloride cement.

[0037] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; microwave-treat the mixture, set the microwave power to 500 W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:50:0.03:5:5:55.

[0038] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0039] Example 3

[0040] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0041] Step 1: Evenly mix 1.0 part of light-burned magnesia (dolomite calcined at 650° C. with an active magnesia content of 18%), 1.5 parts of magnesium chloride (magnesium chloride hexahydrate), and 0.006 parts of apple vinegar to obtain magnesium oxychloride cement.

[0042] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:75:0.05:7.5:7.5:68.

[0043] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0044] Example 4

[0045] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0046] Step 1: Evenly mix 1.0 part of light-burned magnesia (dolomite calcined at 650° C. with an active magnesia content of 18%), 2.0 parts of magnesium chloride (magnesium chloride hexahydrate), and 0.01 part of apple vinegar to obtain magnesium oxychloride cement.

[0047] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; microwave-treat the mixture, set the microwave power to 400 W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:100:0.08:10:10:84.

[0048] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0049] Example 5

[0050] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0051] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 750° C., with an active magnesia content of 45%), 0.8 part of magnesium chloride (magnesium chloride dihydrate), and 0.005 part of apple vinegar to obtain magnesium oxychloride cement.

[0052] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 500W, and treat for 3 minutes. After the microwave treatment is completed, transfer it to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:125:0.1:12.5:12.5:105.

[0053] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0054] Example 6

[0055] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0056] Step 1: Mix 1.0 parts of light-burned magnesia (magnesite calcined at 750° C., with an active magnesia content of 45%), 1.2 parts of magnesium chloride (magnesium chloride dihydrate) and 0.007 parts of apple vinegar to obtain magnesium oxychloride cement.

[0057] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 600W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:150:0.01:15:15:132.

[0058] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0059] Example 7

[0060] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0061] Step 1: Evenly mix 1.0 parts of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 1.8 parts of magnesium chloride (magnesium chloride dihydrate), and 0.009 parts of apple vinegar to obtain magnesium oxychloride cement.

[0062] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 500W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:175:0.03:17.5:17.5:143.

[0063] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0064] Example 8

[0065] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0066] Step 1: Evenly mix 1.0 part of light-burned magnesia (a product of dolomite calcined at 700° C., with an active magnesia content of 25%), 2.0 parts of magnesium chloride (magnesium chloride dihydrate), and 0.01 part of apple vinegar to obtain magnesium oxychloride cement.

[0067] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; microwave-treat the mixture, set the microwave power to 500W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:200:0.05:20:15:150.

[0068] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0069] Example 9

[0070] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0071] Step 1: Evenly mix 1.0 part of light-burned magnesia (a product of dolomite calcined at 700° C., with an active magnesia content of 25%), 1.0 part of magnesium chloride (magnesium chloride dihydrate), and 0.006 part of apple vinegar to obtain magnesium oxychloride cement.

[0072] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 300W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:150:0.08:10:10:126.

[0073] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0074] Example 10

[0075] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0076] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 1.0 part of magnesium chloride (magnesium chloride tetrahydrate), and 0.005 part of apple vinegar to obtain magnesium oxychloride cement.

[0077] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 300W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:120:0.1:8:8:109.

[0078] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0079] Example 11

[0080] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0081] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 2.0 parts of magnesium chloride (magnesium chloride dihydrate), and 0.007 parts of apple vinegar to obtain magnesium oxychloride cement.

[0082] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:180:0.01:14:14:150.

[0083] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0084] Example 12

[0085] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0086] Step 1: Evenly mix 1.0 parts of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 1.8 parts of magnesium chloride (magnesium chloride dihydrate), and 0.006 parts of apple vinegar to obtain magnesium oxychloride cement.

[0087] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:160:0.03:12:12:142.

[0088] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0089] Example 13

[0090] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0091] Step 1: Evenly mix 1.0 part of light-burned magnesia (a product of dolomite calcined at 700° C., with an active magnesia content of 25%), 0.9 part of magnesium chloride (magnesium chloride dihydrate), and 0.004 part of apple vinegar to obtain magnesium oxychloride cement.

[0092] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:140:0.05:9:9:128.

[0093] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0094] Example 14

[0095] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0096] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 1.3 parts of magnesium chloride (magnesium chloride dihydrate), and 0.003 parts of apple vinegar to obtain magnesium oxychloride cement.

[0097] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; microwave-treat the mixture, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:130:0.08:6:6:121.

[0098] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0099] Example 15

[0100] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0101] Step 1: Evenly mix 1.0 parts of light-burned magnesia (a product of dolomite calcined at 700° C., with an active magnesia content of 25%), 1.1 parts of magnesium chloride (magnesium chloride dihydrate), and 0.002 parts of apple vinegar to obtain magnesium oxychloride cement.

[0102] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; microwave-treat the mixture, set the microwave power to 400 W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:110:0.1:4:4:110.

[0103] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0104] Example 16

[0105] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0106] Step 1: Mix 1.0 parts of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 1.5 parts of magnesium chloride (magnesium chloride dihydrate) and 0.007 parts of apple vinegar to obtain magnesium oxychloride cement.

[0107] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:140:0.01:15:15:132.

[0108] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0109] Example 17

[0110] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0111] Step 1: Evenly mix 1.0 parts of light-burned magnesia (a product of dolomite calcined at 700° C., with an active magnesia content of 25%), 1.8 parts of magnesium chloride (magnesium chloride dihydrate), and 0.009 parts of apple vinegar to obtain magnesium oxychloride cement.

[0112] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:175:0.05:17.5:17.5:140.

[0113] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0114] Example 18

[0115] The embodiment of the present invention provides a method for solidifying copper tailings waste using magnesium oxychloride cement, comprising the following steps:

[0116] Step 1: Evenly mix 1.0 part of light-burned magnesia (magnesite calcined at 800° C., with an active magnesia content of 60%), 2.0 parts of magnesium chloride (magnesium chloride dihydrate), and 0.01 part of apple vinegar to obtain magnesium oxychloride cement.

[0117] Step 2: Pre-mix and dissolve carbonic anhydrase with a portion of water, and then mix with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; subject the mixture to microwave treatment, set the microwave power to 400W, and treat for 3 minutes. After the microwave treatment is completed, transfer the mixture to a stirring device for dry mixing, dry mixing for 3 minutes, and then add another portion of water and continue stirring until the mixture is uniformly mixed; wherein the weight ratio of copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:200:0.1:15:15:150.

[0118] Step 3: Inject the slurry mixed evenly in step 2 into a mold or a mine pit, vibrate and compact it, and then perform curing for 7 days. During the entire curing process, a DC electric field of 10 V / cm is continuously applied to the slurry. The specific curing process is the same as in Example 1.

[0119] Comparative Example 1

[0120] This comparative example illustrates a process for solidifying copper tailings waste with silicate cement. The mass ratio of the components is: 100 parts copper tailings, 20 parts silicate cement, and 10 parts water. The main chemical composition of the copper tailings is the same as in Example 1. The silicate cement is ordinary silicate cement with a strength grade of 42.5. The preparation method is as follows: the copper tailings, silicate cement, and water are uniformly mixed, poured into a pre-prepared mold or a mine pit, and vibrated to ensure compaction. The mixture is then naturally solidified and covered with straw bags or film for natural curing to avoid exposure to sunlight. The curing time is at least 7 days to ensure the strength and stability of the solidified body. After demolding, the solidified test piece is obtained.

[0121] The flexural strength, softening coefficient, copper ion leaching concentration and carbonization depth of the cement solidified bodies prepared in Examples 1 to 18 and Comparative Example 1 were tested. The results of the flexural strength, softening coefficient, copper ion leaching concentration after leaching for 1 day and carbonization depth of each component at 28 days and around 20°C are shown in Table 1.

[0122] Table 1 Test performance of solidified copper tailings waste in each embodiment

[0123]

[0124]

[0125] As can be seen from Table 1, the flexural strength and softening coefficient of the cement components prepared by the method of the present invention are higher than those of the comparative example, and the copper ion leaching concentration is much lower than that of the comparative example, indicating that the process of the present invention can have a good solidification effect on copper tailings waste and inhibit the seepage of heavy metal copper ions.

[0126] The present invention provides an efficient and environmentally friendly magnesium oxychloride cement solidification copper tailings process, which significantly improves the strength, durability and heavy metal solidification effect of the solidified body by optimizing the component ratio and curing conditions. Compared with the traditional method, the present invention not only reduces the copper ion leaching concentration to a level far below the environmental protection standard (0.2-0.5mg / L), but also achieves excellent performance of 28-day flexural strength of 8-16MPa, softening coefficient of 0.82-0.96, and copper ion leaching concentration less than 2.0mg / L. In addition, the process of the present invention is simple and low in cost. It does not require complex equipment or high temperature and high pressure conditions, and curing can be completed at room temperature. The solidified copper tailings can be used as building materials, realizes resource utilization, and reduces dependence on natural resources. The present invention has significant economic and environmental benefits in the fields of mine tailings treatment and heavy metal pollution remediation, showing broad application prospects.

[0127] The above are only preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for solidifying copper tailings waste using magnesium oxychloride cement, characterized in that: The following steps are involved: dissolving carbonic anhydrase in water and mixing the mixture with copper tailings, magnesium oxychloride cement, metakaolin and clay to obtain a mixture; The mixture is subjected to microwave treatment, dry mixing is performed after the microwave treatment is completed, and water is added after the dry mixing is completed and further stirred to obtain magnesium oxychloride copper tailings cement.

2. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 1, wherein The weight ratio of the copper tailings, magnesium oxychloride cement, carbonic anhydrase, metakaolin, clay and water is 100:25-200:0.01-0.1:2.5-20:5-15:50-150.

3. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 1, wherein The magnesium oxychloride cement is prepared by mixing light-burned magnesium oxide, magnesium chloride and organic acid; The weight ratio of the light-burned magnesium oxide, magnesium chloride and organic acid is 1.0:0.5-2.0:0.002-0.

01.

4. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 3, wherein The organic acid is apple cider vinegar, the acetic acid content of which is 4% to 6% and the pH value is 2.5 to 3.

5.

5. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 3, wherein The magnesium chloride is a mixture of one or more of magnesium chloride dihydrate, magnesium chloride tetrahydrate and magnesium chloride hexahydrate; The light-burned magnesia is a product of magnesite calcined at 750-1000° C., wherein the active magnesia content is 45%-80%; or the light-burned magnesia is a product of dolomite calcined at 650-780° C., wherein the active magnesia content is 18%-30%.

6. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 1, wherein The copper tailings include 10%-40% SiO2, 5%-20% Fe2O3, 5%-15% CaO, 5%-15% Al2O3, 1%-10% MgO, 0.1%-5% CuO and 0.1%-3% ZnO.

7. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 1, wherein The specific surface area of the metakaolin is greater than 300-500m 2 / kg, activity index greater than 70%; The particle size of the clay is no more than 5 mm, and the moisture content is 1%-15%.

8. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 1, wherein It also includes maintenance operations, specifically: The uniformly mixed magnesium oxychloride copper tailings cement is injected into a mold or a mine pit, vibrated and compacted, and then cured. During the curing process, a direct current electric field is continuously applied to the slurry. The curing process includes carbon dioxide curing and natural curing, and the carbon dioxide curing and natural curing are performed intermittently. After the curing is completed, the magnesium oxychloride copper tailings cement component is obtained.

9. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 8, wherein The carbon dioxide curing is carried out on the 3rd to 5th day of curing, with 2 to 3 periods selected each day, each period lasting 1 to 2 hours, and the solidified body is placed in a carbon dioxide environment with a carbon dioxide concentration of 10% to 20%; During the natural curing period outside the carbon dioxide curing period, the solidified body is covered with straw bags or films to avoid exposure to sunlight.

10. The method for solidifying copper tailings waste using magnesium oxychloride cement according to claim 8, wherein: The prepared copper tailings magnesium oxychloride cement component is used as a road base material or a mine backfill material.

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