Iron tailings powder-based cementing material for mine full tailings cemented filling, and preparation method and application thereof

Abstract

The present application belongs to the technical field of underground filling of metal mines, and particularly relates to an iron tailings powder-based cementitious material for mine full tailings cemented filling, a preparation method and application thereof. The geopolymer-based anti-cracking mortar is made of iron tailings ultrafine powder, ore powder, sulphoaluminate clinker, Portland cement clinker, desulfurization gypsum and methyl cellulose ether. The iron tailings powder-based cementitious material can completely replace ordinary Portland cement in full tailings filling and achieve better cementing effect than cement, thereby greatly reducing the consumption of cement and other cementitious materials, lowering the filling cost, reducing carbon emissions and increasing the utilization rate of tailings. The rheological properties, mechanical properties and durability of the full tailings cemented filling material made of the iron tailings powder-based cementitious material can meet the requirements of mine filling, and the material can achieve the effect of expansion and roof contact without adding external additives, thereby solving the shrinkage problem of cement-based filling materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of underground filling in metal mines, and particularly relates to an iron tailings powder-based cementitious material for mine full tailings cemented filling, and a preparation method and application thereof. BACKGROUND

[0002] For many years, China's total crude steel output has ranked first in the world. At the same time, China is also the country with the largest stock of metal tailings in the world. Although the comprehensive utilization rate of tailings in China has improved in recent years, the stock is still increasing year by year. Among them, the largest proportion is metal tailings, and the largest proportion of single type is iron tailings. The discharge amount of iron tailings accounts for the highest proportion in the total tailings discharge amount, and is continuously increasing.

[0003] At present, one of the main disposal methods for consuming the above-mentioned tailings is to mix these tailings with a certain proportion of cement or cementing powder to prepare cemented filling materials for filling in the mined-out area of the mine. In the traditional cemented filling material, the aggregate of the full tailings cemented filling body is the full particle size tailings without desliming in the concentrator, and the cementitious material usually adopts ordinary portland cement, and the two are uniformly stirred with water in a certain proportion to form a filling slurry, which is transported to the underground mined-out area through a pipeline. Although the total output of cement in China is high, the manufacturing process of cement is a high-carbon emission process, and the use of cement not only increases the cost of tailings treatment, but also increases carbon emissions. This will make the tailings treatment technology and the production process of full tailings cemented filling material in China face new problems and challenges. SUMMARY

[0004] In view of the above technical problems, the present application provides an iron tailings powder-based cementitious material for mine full tailings cemented filling, and a preparation method and application thereof. The iron tailings powder-based cementitious material provided by the present application can completely replace ordinary portland cement in full tailings filling and achieve better cementation effect than cement, thereby reducing the consumption of cement, reducing the cost and reducing carbon emissions.

[0005] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0006] The present application provides an iron tailings powder-based cementitious material for full tailings cemented filling, and the raw materials thereof include, in terms of weight fraction: 500-550 parts of iron tailings ultrafine powder, 300-350 parts of mineral powder, 20-30 parts of sulphoaluminate clinker, 100-120 parts of portland cement clinker, 80-100 parts of desulfurized gypsum, and 10-15 parts of methyl cellulose ether, wherein the D50 of the iron tailings ultrafine powder is ≤5 μm, and contains 0.1%-0.3%wt of grinding aid.

[0007] Compared with the cement material used as a binder in a traditional full tailings cemented filling body, the above-mentioned iron tailings powder-based cementitious material provided by the present application can completely replace ordinary Portland cement in full tailings filling and can achieve an effect superior to cement consolidation, thereby greatly reducing the consumption of cement and other cementitious materials, reducing filling costs, reducing carbon emissions, increasing tailings utilization, and achieving the production purposes of low carbon, safety, and high efficiency.

[0008] The full tailings cemented filling material prepared by using the above-mentioned iron tailings powder-based cementitious material provided by the present application not only has rheological properties, mechanical properties, and durability that can meet the requirements of mine filling, but also can achieve the effect of swelling and abutting by relying on its own characteristics without adding additives, thereby solving the shrinkage problem of cement-based filling materials.

[0009] The iron tailings ultrafine powder in the iron tailings powder-based cementitious material of the present application can be obtained by jointly grinding the iron tailings and a grinding aid. The iron tailings ultrafine powder with D50≤5 μm is a component material of the cementitious material, and can produce the following four effects with other raw materials under the above-mentioned ratio, thereby effectively improving the mechanical properties and volume stability of the consolidated body made of the iron tailings powder-based cementitious material: (1) the activity effect of ultrafine particle size micro powder: the surface of the iron tailings ultrafine powder with D50≤5 μm has a large amount of amorphous SiO2 and Al2O3 components, which can rapidly hydrate to generate hydraulic hydration products in an alkaline environment, and the mutual cementation between the hydration products can generate mechanical strength; (2) the grading synergy effect of ultrafine particle size iron tailings micro powder and raw tailings: the ultrafine particles in the iron tailings ultrafine powder with D50≤5 μm can fill the voids formed after the accumulation of large particle tailings in the consolidated body, improve the compactness of the filling body, and at the same time, reduce the spatial distance between solid particles, thereby improving the cementation efficiency of the hydration products; (3) the role of providing nucleation sites for the non-uniform nucleation of hydration products: the surface activation degree of the medium particle size particles in the iron tailings ultrafine powder with D50≤5 μm is lower than that of the ultrafine particles, and the amount of dissolved active components is relatively small, but the particle surface still has chemical bond breaking sites of silicon and aluminum components, which become non-uniform nucleation sites for the initial generation of hydration products, effectively reducing the nucleation barrier of the hydration products, and being conducive to the growth of the hydration products on the surface of the medium particle size tailings particles. At the same time, the hydration products generated at these sites are cemented with other hydration products, increasing the bonding force between the tailings particles and improving the mechanical strength of the consolidated body; (4) the micro aggregate effect of the internal crystalline part of the hydration product layer: after the activated components on the surface of the iron tailings ultrafine powder are dissolved and hydrated, the internal crystalline minerals remain in a stable state of inertia, which acts as a micro aggregate in the consolidated body, effectively offsets the volume shrinkage and other volume changes caused by the evaporation of water after the hydration of the consolidated body in the later stage, and plays a role in stabilizing the volume change of the filling body.

[0010] The application finds, through experimental research, that the activity index of D50 and the iron tailings superfine powder has a high negative correlation, mainly in the form of a negative correlation with the activation rate of the silicon-aluminum mineral composition in the iron tailings superfine powder. The application controls the D50 value to precisely regulate the activity of the iron tailings superfine powder, so that the above-mentioned activity effect is exerted.

[0011] In the application, the cement clinker content is only 22% to 30% of the iron tailings superfine powder. The content of the sulphoaluminate clinker in the cement clinker can affect the number of ettringite crystal nuclei in the early stage, so as to control the expansion rate of the cemented filling material prepared from the iron tailings powder-based cementitious material. The portland cement clinker supplements part of the hydration products, calcium silicate hydrate and ettringite, in the hydration process. Since the portland cement clinker is a hydraulic cementitious material, the anti-fresh water erosion ability of the cemented filling material prepared from the iron tailings powder-based cementitious material can be effectively improved.

[0012] The mixing ratio of the sulphoaluminate clinker to the portland cement clinker is 1:6 to 1:3.3. If the ratio is too high, the cementitious material will appear to be rapidly setting. If the ratio is too low, there will be no effect, and the AFt crystal nuclei and the expansion effect of the sulphoaluminate cement clinker cannot be exerted.

[0013] The desulfurization gypsum can provide the SO4 2- ion required in the hydration process of the iron tailings powder-based cementitious material, excite the dissolution and hydration of the active Al2O3 in the iron tailings superfine powder and the metal tailings for filling, and supplement the hydration products C-S-H and AFt in the hydration process.

[0014] In combination with the first aspect, the mineral composition in the iron tailings superfine powder used in the application includes quartz, potassium feldspar, sodium feldspar and biotite.

[0015] Preferably, the content of the quartz in the iron tailings superfine powder is 20wt% to 25wt%, the content of the potassium feldspar is 25wt% to 35wt%, the content of the sodium feldspar is 20wt% to 30wt%, the content of the biotite is 5wt% to 10wt%, and the balance is other minerals.

[0016] Experiments show that, in the grinding and activation process, the diffraction peak of the potassium feldspar decreases at the fastest speed, which indicates that the potassium feldspar has a higher degree of amorphization and higher activity after grinding and activation. Therefore, the higher the content of the potassium feldspar in the iron tailings superfine powder, the better the activity of the iron tailings superfine powder after activation, and the better the performance of the iron tailings powder-based cementitious material for full-tailings consolidation prepared.

[0017] In combination with the first aspect, the iron tailings ultrafine powder used in the application comprises the following chemical components in mass percentage: 55-60% of SiO2, 5-15% of Al2O3, 14-20% of Fe2O3, 2-3% of CaO, 2-3% of MgO, 2-3% of K2O, 2-3% of Na2O and 1-3% of SO3.

[0018] In combination with the first aspect, the mineral powder used in the application is S95 grade mineral powder with a specific surface area of 420-450 m 2 / kg.

[0019] The S95 grade mineral powder with a specific surface area of 420-450 m 2 / kg can participate in the secondary hydration of the iron tailings powder-based cementitious material, and supplement the active silica-aluminum components required for the late hydration of the iron tailings powder-based cementitious material.

[0020] In combination with the first aspect, the sulphoaluminate clinker used in the application meets the sulphoaluminate clinker standard GB / T37125-2018, has an alkalinity coefficient (cm) of 0.9-1.0 and an aluminum-sulfur ratio (Ps) of 3.5-4.0.

[0021] The above-mentioned sulphoaluminate clinker can rapidly generate a large number of fine ettringite grains in the early hydration stage of the iron tailings powder-based cementitious material, provide crystal nuclei for the ettringite generated by the hydration of the iron tailings ultrafine powder in the iron tailings powder-based cementitious material, and increase the swelling component in the full tailings solidified body. By adjusting the content of the sulphoaluminate cement clinker, the top contact rate of the full tailings cemented filling body can be accurately controlled.

[0022] In combination with the first aspect, the portland cement clinker used in the application meets the portland cement clinker national standard GB / T21372-2008.

[0023] The above-mentioned portland cement clinker can provide the alkaline component required in the hydration process of the iron tailings powder-based cementitious material, and supplement part of the hydration products, hydrated calcium silicate and ettringite, in the hydration process. Since the portland cement clinker is a hydraulic cementitious material, the incorporation of a small amount of the portland cement clinker can effectively improve the resistance of the full tailings cemented filling body to fresh water corrosion.

[0024] In combination with the first aspect, the grinding aid used in the application comprises at least one of triethanolamine, triisopropanolamine, sodium metasilicate and sodium hexametaphosphate.

[0025] Preferably, the grinding aid used in the application is sodium hexametaphosphate. It has been found through experimental research that sodium hexametaphosphate has the best grinding effect on feldspar minerals in the iron tailings powder, and the feldspar minerals in the iron tailings powder are the fastest to be amorphized in the grinding process. The finer the feldspar minerals in the iron tailings powder are ground, the higher the activity of the activated iron tailings ultrafine powder is.

[0026] Preferably, the sodium hexametaphosphate is in powder form, and the specific surface area is 200-230 m 2 / kg, which plays a role of grinding aid in the ultrafine grinding process of the metal tailing, eliminates the agglomeration of the ultrafine metal tailing powder, and plays a role of dispersing the solid particles in the slurry during the transportation of the full tailings cemented filling material slurry, prevents the settlement and bleeding, and effectively improves the rheological property of the filling material slurry.

[0027] In combination with the first aspect, the methyl cellulose ether used in the application is in powder form, and the specific surface area is 200-210 m 2 / kg. The methyl cellulose ether can play a role of improving the morphology of ettringite in the hydration process of the iron tailing powder-based cementitious material, and can effectively control the aspect ratio of ettringite crystals. After the incorporation of the powder methyl cellulose ether with the specific surface area of 200-210 m 2 / kg, the aspect ratio of ettringite in the slurry becomes larger, and the morphology is fine needle rod-shaped, which can reduce the expansion caused by the crystallization pressure in the growth process of ettringite crystals, and effectively improve the crack resistance of the filling body.

[0028] In combination with the first aspect, the D50 of the iron tailing ultrafine powder used in the application is 3-5 μm. The surface activity of the iron tailing ultrafine powder is significantly increased when the D50 is less than 5 μm, but the decrease of the D50 will increase the grinding cost and reduce the economic efficiency. The control of the D50 of the iron tailing ultrafine powder to 3-5 μm can meet the activity requirements and at the same time can take into account the production cost.

[0029] The second aspect of the application provides a preparation method of the above-mentioned iron tailing powder-based cementitious material for full tailings cementation, which specifically comprises the following steps:

[0030] S1, drying the iron tailing powder and then grinding the iron tailing powder after the addition of the grinding aid to obtain an iron tailing ultrafine powder;

[0031] S2, mixing and grinding the sulphate aluminate clinker, the silicate cement clinker and the methyl cellulose ether to obtain a cement clinker mixture;

[0032] S3, uniformly mixing the iron tailing ultrafine powder with the cement clinker mixture, the mineral powder and the desulfurization gypsum to obtain the iron tailing powder-based cementitious material for full tailings cementation.

[0033] The above-mentioned preparation method provided by the application has simple process, strong operability and practicability, and no harmful substances to the environment are used and produced in the process of treating the iron tailing powder, and 90% of the raw materials can be selected from solid waste materials, which meets the requirements of green environmental protection.

[0034] In the present application, the iron tailings powder is ground separately from the cement clinker. Compared with the cement clinker, the iron tailings need to add sodium hexametaphosphate grinding aid to improve the grinding efficiency. Moreover, the iron tailings need to be ground to a powder particle size median D50≤5 μm, and then a large amount of amorphous active substances will be generated. The cement clinker is ground to a specific surface area of 350-400 m 2 / kg, and grinding too fine will cause the early hydration speed to be too fast, the volume shrinkage to be large, and the filling performance of the solidified material to be affected. Separate grinding can also make the methyl cellulose ether more uniformly distributed on the surface of the cement clinker, and the modification effect of the cement clinker is better.

[0035] In combination with the second aspect, the temperature of the drying in S1 is 100-105℃, and the drying is performed until the moisture content is ≤1.5wt%.

[0036] In combination with the second aspect, the rotation speed of the grinding in S1 is 45-55 r / min, and the grinding time is 150-180 min.

[0037] Exemplarily, the grinding is performed on a test mill, and the test mill is a 5 kg cement test mill, and the model is By controlling the rotation speed and the grinding time of the test mill, the iron tailings superfine powder with the highest activity can be obtained. If the grinding time is too short, the iron tailings powder cannot be fully ground. If the grinding time is too long, the internal cracks of the iron tailings powder particles begin to appear "compaction" and "welding" phenomena, resulting in a decrease in the specific surface area of the iron tailings powder, and thus a decrease in the reaction activity. After adding the grinding aid, the "compaction" and "welding" phenomena can be greatly delayed, the grinding efficiency can be improved, and the required iron tailings superfine powder can be obtained.

[0038] In the existing research on mechanical activation of tailings, the specific surface area of the tailings after grinding is rarely above 1000 m 2 / kg. Experimental research shows that when the specific surface area of the iron tailings is greater than 800 m 2 / kg during the grinding process, further grinding is prone to agglomeration, which in turn causes the specific surface area to decrease with the extension of the grinding time. By adding a grinding aid, the agglomeration problem can be effectively solved, but it is difficult to improve the specific surface area to above 1000 m 2 / kg. The present application finds that although the specific surface area of the iron tailings powder appears a bottleneck phenomenon during the grinding process, the particle size median D50 unidirectionally decreases with the extension of the grinding time. After 150-180 min of grinding, the obtained iron tailings superfine powder has a D50 value of 3-5 μm and a specific surface area of 900-1000 m 2 / kg. During the grinding process, the number of "unsaturated bonds" on the surface of the iron tailings particles increases with the decrease of the D50 value, causing the distortion of the surface crystal lattice. With the increase of the distortion degree, the surface silicon-aluminum components are transformed from the amorphous state to the active state, which has the hydration activity.

[0039] In combination with the second aspect, the rotation speed of the grinding in S2 is 45-55 r / min, and the grinding time is 50-70 min.

[0040] Exemplarily, the grinding is performed on a test mill, which is a 5 kg cement test mill, and the model is The grinding time on the test mill is controlled to be 50-70 min. If the grinding time is too long, the clinker mixture will be too fine, the hydration speed will be fast, the early hydration heat will be large, the volume shrinkage will be large, and the filling performance of the solidified material will be affected. If the grinding time is too short, the mixture will not be fully ground. The specific surface area of the clinker mixture after grinding is 380-420 m 2 / kg.

[0041] The third aspect of the present application provides an application of the above-mentioned iron tailings powder-based cementitious material or the iron tailings powder-based cementitious material prepared by the above-mentioned preparation method in the preparation of a full tailings cemented filling material.

[0042] The fourth aspect of the present application provides a full tailings cemented filling material, and the raw materials thereof include, by weight fraction, 180-200 parts of the above-mentioned iron tailings powder-based cementitious material, 630-660 parts of water, and 1200-1300 parts of metal tailings.

[0043] In combination with the fourth aspect, the metal tailings used in the present application can be the iron tailings powder used in the preparation of the iron tailings powder-based cementitious material, or other metal tailings. When other metal tailings are used, the performance of the full tailings cemented filling material is not significantly affected.

[0044] The fifth aspect of the present application provides a preparation method of the above-mentioned full tailings cemented filling material, which specifically includes the following operation: uniformly mixing the iron tailings powder-based cementitious material, water, and metal tailings to obtain the full tailings cemented filling material. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The XRD graph of the iron tailings ultrafine powder used in Example 1 of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with specific examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0047] In the process of using tailings to make cemented filling material for filling the mined-out area of a mine, ordinary Portland cement is usually used as the cementitious material. However, the manufacturing process of cement is a high-carbon-emission process, and the use of cement not only increases the cost of tailings treatment, but also increases carbon emissions.

[0048] To solve the above problems, the present application has carried out a large number of experimental researches on the cementitious raw materials and preparation process of mine cementation, and obtained an iron tailings powder-based cementitious material for full tailings cementation, the raw materials of which include, in parts by weight: 500-550 parts of iron tailings ultrafine powder, 300-350 parts of mineral powder, 20-30 parts of sulphoaluminate clinker, 100-120 parts of Portland cement clinker, 80-100 parts of desulfurized gypsum and 10-15 parts of methyl cellulose ether, wherein the D50 of the iron tailings ultrafine powder is ≤5 μm, and contains 0.1%-0.3%wt of grinding aid.

[0049] In the embodiment of the present application, the mineral components in the iron tailings ultrafine powder include quartz, potassium feldspar, sodium feldspar and biotite.

[0050] In order to obtain higher activity, in the embodiment of the present application, the content of quartz in the iron tailings ultrafine powder is 20wt%-25wt%, the content of potassium feldspar is 25wt%-35wt%, the content of sodium feldspar is 20wt%-30wt%, the content of biotite is 5wt%-10wt%, and the balance is other minerals.

[0051] In terms of chemical composition, the iron tailings ultrafine powder includes the following mass percentage of chemical components: 55%-60% of SiO2, 5%-15% of Al2O3, 14%-20% of Fe2O3, 2%-3% of CaO, 2%-3% of MgO, 2%-3% of K2O, 2%-3% of Na2O and 1%-3% of SO3.

[0052] In the embodiment of the present application, the mineral powder is S95 grade mineral powder, and the specific surface area is 420-450 m 2 / kg.

[0053] In the embodiment of the present application, the sulphoaluminate clinker meets the sulphoaluminate clinker standard GB / T37125-2018, the alkalinity coefficient (cm) is 0.9-1.0, and the aluminum-sulfur ratio (Ps) is 3.5-4.0; the Portland cement clinker meets the national standard GB / T21372-2008 for Portland cement clinker.

[0054] In the embodiment of the present application, the grinding aid includes at least one of triethanolamine, triisopropanolamine, sodium metasilicate and sodium hexametaphosphate. As a preferred embodiment, the grinding aid is sodium hexametaphosphate. As a preferred embodiment, the sodium hexametaphosphate is in powder form, and the specific surface area is 200-230 m 2 / kg.

[0055] In the embodiment of the present application, the methyl cellulose ether is in powder form, and the specific surface area is 200-210 m 2 / kg.

[0056] The embodiment of the present application also provides a preparation method of the iron tailings powder-based cementitious material for full tailings cementation.

[0057] S1, drying the iron tailings powder and adding the grinding aid to obtain an iron tailings superfine powder;

[0058] S2, mixing and grinding the sulphate aluminate clinker, the silicate cement clinker and the methyl cellulose ether to obtain a cement clinker mixture;

[0059] S3, uniformly mixing the iron tailings superfine powder, the cement clinker mixture, the mineral powder and the desulfurization gypsum to obtain the iron tailings powder-based cementitious material for full tailings cementation.

[0060] The embodiment of the present application also provides a full tailings cementation filling material made of the iron tailings powder-based cementitious material and a preparation method thereof, and raw materials thereof include the iron tailings powder-based cementitious material 180-200 parts, water 630-660 parts and metal tailings 1200-1300 parts by weight.

[0061] The embodiment of the present application is further described in the following multiple embodiments.

[0062] In the following embodiments, the main mineral components in the iron tailings powder are quartz, potassium feldspar, sodium feldspar and biotite, and the XRD graph of the iron tailings powder used in each embodiment is shown in Figure 1 .

[0063] The test mill used in the following embodiments is a 5 kg cement test mill, and the model is

[0064] Embodiment 1

[0065] The embodiment of the present application provides an iron tailings powder-based cementitious material for full tailings cementation and a preparation method thereof.

[0066] Take 500 parts of the iron tailings powder and place it in an oven, the drying temperature is 100℃, the drying time is 10h, and the moisture content after drying is ≤1.5wt%;

[0067] Take 0.5 parts of the grinding aid (sodium hexametaphosphate) and uniformly mix it with the dried iron tailings powder, then place it in a test mill for grinding, the rotation speed of the test mill is 45r / min, the grinding time is 150min, and an iron tailings superfine powder is obtained, the median particle size of the iron tailings superfine powder is 4.92μm;

[0068] Take 20 parts of sulphoaluminate clinker, 120 parts of portland cement clinker and 15 parts of methyl cellulose ether, mix uniformly, then put into the test mill for grinding, the speed of the test mill is 45 r / min, the grinding time is 50 min, and the clinker mixture is obtained;

[0069] Mix the iron tailings ultrafine powder, mineral powder, clinker mixture and desulfurized gypsum uniformly to obtain the iron tailings powder-based cementitious material A1 for full tailings cementation.

[0070] Among them, the content of quartz in the iron tailings powder is 24.2%, the content of potassium feldspar is 31.1%, the content of sodium feldspar is 23.8%, the content of biotite is 6.2%, and the balance is other minerals; the chemical composition and mass percentage in the iron tailings powder are: 58.9% of SiO2, 14.3% of Al2O3, 15.6% of Fe2O3, 3.0% of CaO, 2.2% of MgO, 2.1% of K2O, 2.4% of Na2O and 2.3% of SO3; the mineral powder is S95 grade mineral powder with a surface area of 430 m 2 / kg; the sulphoaluminate clinker meets the sulphoaluminate clinker standard GB / T37125-2018, the basicity coefficient (cm) is 0.98, and the aluminum-sulfur ratio (Ps) is 3.5; the portland cement clinker meets the national standard GB / T21372-2008 for portland cement clinker; the sodium hexametaphosphate is in powder form with a specific surface area of 220 m 2 / kg; the methyl cellulose ether is in powder form with a specific surface area of 200 m 2 / kg.

[0071] Example 2

[0072] The present application provides a preparation method of an iron tailings powder-based cementitious material for full tailings cementation:

[0073] Take 550 parts of iron tailings powder and put it into an oven, the drying temperature is 110℃, the drying time is 12h, and the water content after drying is ≤1.5wt%.

[0074] Take 1 part of grinding aid (sodium hexametaphosphate) and mix it uniformly with the dried iron tailings powder, then put it into the test mill for grinding, the speed of the test mill is 55 r / min, the grinding time is 180 min, and the iron tailings ultrafine powder is obtained, the median particle size of which is 3.76μm.

[0075] Take 30 parts of sulphoaluminate clinker, 120 parts of portland cement clinker and 10 parts of methyl cellulose ether, mix uniformly, then put into the test mill for grinding, the speed of the test mill is 55 r / min, the grinding time is 70 min, and the clinker mixture is obtained.

[0076] The iron tailings ultrafine powder, the mineral powder, the clinker mixture and the desulfurization gypsum are uniformly mixed to obtain an iron tailings powder-based cementitious material A2 for full tailings cementation.

[0077] The content of quartz in the iron tailings powder is 24.8%, the content of potassium feldspar is 34.8%, the content of sodium feldspar is 20.4%, the content of biotite is 5.2%, and the balance is other minerals; the chemical composition and mass percentage in the iron tailings powder are as follows: 55.4% of SiO2, 14.8% of Al2O3, 14.2% of Fe2O3, 2.3% of CaO, 2.9% of MgO, 2.3% of K2O, 2.1% of Na2O and 1.3% of SO3; the mineral powder is S95 grade mineral powder with a surface area of 420 m 2 / kg; the sulphoaluminate clinker meets the sulphoaluminate clinker standard GB / T37125-2018, the basicity coefficient (cm) is 1.00, and the aluminum-sulfur ratio (Ps) is 4.0; the Portland cement clinker meets the Portland cement clinker national standard GB / T21372-2008; the sodium hexametaphosphate is in powder form with a specific surface area of 200 m 2 / kg; the methyl cellulose ether is in powder form with a specific surface area of 205 m 2 / kg.

[0078] Example 3

[0079] The application provides a preparation method of an iron tailings powder-based cementitious material for full tailings cementation.

[0080] Take 500 parts of the iron tailings powder and place it in an oven, the drying temperature is 110 DEG C, the drying time is 10 h, and the moisture content after drying is less than or equal to 1.5 wt%.

[0081] Take 1.5 parts of the grinding aid (sodium hexametaphosphate) and mix it uniformly with the dried iron tailings powder, then place it in a test mill and grind, the rotating speed of the test mill is 45 r / min, the grinding time is 180 min, and the iron tailings ultrafine powder is obtained, the median particle size of the iron tailings ultrafine powder is 4.24 mu m.

[0082] Take 20 parts of the sulphoaluminate clinker, 100 parts of the Portland cement clinker and 13 parts of the methyl cellulose ether, mix them uniformly and then place them in a test mill and grind, the rotating speed of the test mill is 45 r / min, the grinding time is 70 min, and the clinker mixture is obtained.

[0083] The iron tailings ultrafine powder, the mineral powder, the clinker mixture and the desulfurization gypsum are uniformly mixed to obtain an iron tailings powder-based cementitious material A3 for full tailings cementation.

[0084] The content of quartz in the iron tailings powder is 20.4%, the content of potassium feldspar is 25.2%, the content of sodium feldspar is 29.7%, the content of biotite is 9.7%, and the balance is other minerals; the chemical composition and mass percentage in the iron tailings powder are as follows: 59.6% of SiO2, 5.3% of Al2O3, 19.7% of Fe2O3, 2.7% of CaO, 2.6% of MgO, 2.9% of K2O, 2.6% of Na2O and 2.7% of SO3; the mineral powder is S95 grade mineral powder with a surface area of 450 m 2 / kg; the sulphoaluminate clinker meets the sulphoaluminate clinker standard GB / T37125-2018, the basicity coefficient (cm) is 0.91, and the aluminum-sulfur ratio (Ps) is 3.7; the Portland cement clinker meets the Portland cement clinker national standard GB / T21372-2008; the sodium hexametaphosphate is in powder form, and the specific surface area is 230 m 2 / kg; the methyl cellulose ether is in powder form, and the specific surface area is 210 m 2 / kg.

[0085] Example 4

[0086] The embodiment of the present application provides a method for preparing full tailings cemented filling material by using iron tailings powder based cementitious material:

[0087] Step a: according to the mass fraction, the iron tailings powder based cementitious material (A1) 200 parts, water 660 parts and metal tailings 1200 parts are weighed and prepared;

[0088] Step b: the prepared material is put into a concrete mixer and stirred uniformly to obtain a full tailings cemented filling material mixture;

[0089] Step c: the full tailings cemented filling material mixture is filled into a mold, demolded after 48 hours, and cured under standard curing conditions (20±2℃, 95%±5% relative humidity) to obtain a full tailings cemented filling material test block B1.

[0090] Example 5

[0091] The embodiment of the present application provides a method for preparing full tailings cemented filling material by using iron tailings powder based cementitious material:

[0092] Step a: according to the mass fraction, the iron tailings powder based cementitious material (A2) 190 parts, water 630 parts and metal tailings powder 1300 parts are weighed and prepared;

[0093] Step b: the prepared material is put into a concrete mixer and stirred uniformly to obtain a full tailings cemented filling material mixture;

[0094] Step c: the full tailings cemented filling material mixture is filled into a mold, demolded after 48 h, and cured under standard curing conditions (20±2℃, 95%±5% relative humidity) to obtain a full tailings cemented filling material test block B2.

[0095] Example 6

[0096] The embodiment of the present application provides a method for preparing a full tailings cemented filling material by using an iron tailings powder-based cementitious material.

[0097] Step a: 180 parts of the iron tailings powder-based cementitious material (A3), 640 parts of water and 1300 parts of the metal tailings powder are weighed according to the mass fraction, and the materials are prepared;

[0098] Step b: the prepared materials are uniformly stirred in a concrete mixer to obtain a full tailings cemented filling material mixture;

[0099] Step c: the full tailings cemented filling material mixture is filled into a mold, demolded after 48 h, and cured under standard curing conditions (20±2℃, 95%±5% relative humidity) to obtain a full tailings cemented filling material test block B2.

[0100] Comparative Example 1

[0101] The comparative example provides a preparation method of a cement-based cemented filling material.

[0102] Step a: 200 parts of the 32.5 composite portland cement, 660 parts of water and 1200 parts of the metal tailings are weighed according to the mass fraction, and the materials are prepared;

[0103] Step b: the prepared materials are uniformly stirred in a concrete mixer to obtain a cement-based cemented filling material;

[0104] Step c: the cement-based cemented filling material is filled into a mold, demolded after 48 h, and cured under standard curing conditions (20±2℃, 95%±5% relative humidity) for 28 d to obtain a full tailings cemented filling material test block S1.

[0105] Comparative Example 2

[0106] The comparative example provides a preparation method of a cement-based cemented filling material.

[0107] Step a: 600 parts of the 42.5 ordinary portland cement, 15 parts of water and 1500 parts of the metal tailings powder are weighed according to the mass fraction, and the materials are prepared;

[0108] Step b: the prepared materials are uniformly stirred in a concrete mixer to obtain a cement-based cemented filling material;

[0109] Step c: the cement-based cemented filling material is filled into a mold, demolded after 48 h, and cured under standard curing conditions (20 ± 2 ℃, 95% ± 5% relative humidity) for 28 d to obtain a full tailings cemented filling material test block S2.

[0110] Comparative Example 3

[0111] 500 parts of iron tailings powder (same as in Example 1) are placed in an oven, the drying temperature is 100 ℃, the drying time is 10 h, and the moisture content after drying is ≤1.5 wt%.

[0112] 0.5 parts of grinding aid (sodium hexametaphosphate) are mixed with the dried iron tailings powder, and then placed in a test mill for grinding, the test mill speed is 45 r / min, and the grinding time is 120 min to obtain iron tailings fine powder, the median particle size of the iron tailings ultrafine powder is 8.38 μm.

[0113] 20 parts of sulphoaluminate clinker, 120 parts of Portland cement clinker, and 15 parts of methyl cellulose ether are mixed uniformly and then placed in a test mill for grinding, the test mill speed is 45 r / min, and the grinding time is 50 min to obtain a clinker mixture.

[0114] The iron tailings ultrafine powder is mixed with the mineral powder, the clinker mixture, and the desulfurized gypsum to obtain an iron tailings powder-based cementitious material D1.

[0115] The D1 is made into a full tailings cemented filling material according to the following steps:

[0116] Step a: 200 parts of iron tailings powder-based cementitious material (D1), 660 parts of water, and 1200 parts of metal tailings are weighed according to the mass fraction, and the materials are prepared;

[0117] Step b: the prepared materials are placed in a concrete mixer and stirred uniformly to obtain a full tailings cemented filling material mixture;

[0118] Step c: the full tailings cemented filling material mixture is filled into a mold, demolded after 48 h, and cured under standard curing conditions (20 ± 2 ℃, 95% ± 5% relative humidity) to obtain a full tailings cemented filling material test block E1.

[0119] Comparative Example 4

[0120] 500 parts of iron tailings powder (same as in Example 1) are placed in an oven, the drying temperature is 100 ℃, the drying time is 10 h, and the moisture content after drying is ≤1.5 wt%.

[0121] Take the grinding aid (sodium hexametaphosphate) 0.5 parts and the dried iron tailings powder mixed evenly after put into the test mill, the speed of the test mill is 45r / min, the grinding time is 150min, get the iron tailings powder, this iron tailings ultrafine powder median particle size is 4.92μm.

[0122] Take the sulphate aluminate clinker 140 parts and methyl cellulose ether 15 parts, mix evenly after put into the test mill, the speed of the test mill is 45r / min, the grinding time is 50min, get the clinker mixture.

[0123] Mix the iron tailings ultrafine powder with the ore powder, clinker mixture and desulfurization gypsum evenly, get the iron tailings powder-based cementitious material D2.

[0124] Make D2 into full tailings cemented filling material according to the following steps:

[0125] Step a: take the iron tailings powder-based cementitious material (D2) 200 parts, water 660 parts, metal tailings 1200 parts according to the mass fraction. Prepare the materials;

[0126] Step b: put the prepared materials into the concrete mixer and mix evenly, get the full tailings cemented filling material mixture;

[0127] Step c: fill the full tailings cemented filling material mixture into the mold, demold after 48h, and get the full tailings cemented filling material test block E2 under the standard curing conditions (20±2℃, 95%±5% relative humidity).

[0128] Comparative example 5

[0129] Take the iron tailings powder (same as example 1) 500 parts and put it into the oven, the drying temperature is 100℃, the drying time is 10h, the moisture content after drying is ≤1.5wt%.

[0130] Take the grinding aid (sodium hexametaphosphate) 0.5 parts and the dried iron tailings powder mixed evenly after put into the test mill, the speed of the test mill is 45r / min, the grinding time is 150min, get the iron tailings powder, this iron tailings ultrafine powder median particle size is 4.92μm.

[0131] Take the sulphate aluminate clinker 140 parts and methyl cellulose ether 15 parts, mix evenly after put into the test mill, the speed of the test mill is 45r / min, the grinding time is 50min, get the clinker mixture.

[0132] Mix the iron tailings ultrafine powder with the ore powder, clinker mixture and desulfurization gypsum evenly, get the iron tailings powder-based cementitious material D3.

[0133] Make D3 into full tailings cemented filling material according to the following steps:

[0134] Step a: Take iron tailings powder-based cementitious material (D3) 200 parts, water 660 parts, and metal tailings 1200 parts by mass fraction. Prepare the materials;

[0135] Step b: Put the prepared materials into a concrete mixer and mix uniformly to obtain a full tailings cemented filling material mixture;

[0136] Step c: Fill the full tailings cemented filling material mixture into a mold, demold after 48 hours, and cure under standard curing conditions (20±2℃, 95%±5% relative humidity) to obtain a full tailings cemented filling material test block E3.

[0137] Comparative Example 6

[0138] Take 500 parts of iron tailings powder (same as Example 1) and place it in an oven. The drying temperature is 100℃, and the drying time is 10h. After drying, the moisture content is ≤1.5wt%.

[0139] Take 0.5 parts of grinding aid (sodium hexametaphosphate) and mix it uniformly with the dried iron tailings powder. Then place it in a test mill and grind it at a speed of 45r / min for 150min to obtain iron tailings fine powder. The median particle size of the iron tailings fine powder is 4.92μm.

[0140] Take 120 parts of sulphoaluminate clinker, 20 parts of Portland cement clinker, and 15 parts of methyl cellulose ether, mix them uniformly, and then place them in a test mill and grind them at a speed of 45r / min for 50min to obtain a clinker mixture.

[0141] Mix the iron tailings ultrafine powder with the mineral powder, clinker mixture, and desulfurized gypsum uniformly to obtain an iron tailings powder-based cementitious material D1.

[0142] Prepare D1 into a full tailings cemented filling material by the following steps:

[0143] Step a: Take iron tailings powder-based cementitious material (D1) 200 parts, water 660 parts, and metal tailings 1200 parts by mass fraction. Prepare the materials;

[0144] Step b: Put the prepared materials into a concrete mixer and mix uniformly to obtain a full tailings cemented filling material mixture;

[0145] Step c: Fill the full tailings cemented filling material mixture into a mold, demold after 48 hours, and cure under standard curing conditions (20±2℃, 95%±5% relative humidity) to obtain a full tailings cemented filling material test block E1.

[0146] Test Example

[0147] 1. The mechanical properties of the filling materials of Examples 4-6 and Comparative Examples 1-6 were detected according to GB / T 17671-2021 Cement mortar strength test method, and the results are shown in Table 1.

[0148] Table 1 Mechanical property test results

[0149]

[0150]

[0151] 2. The expansion rates of the filling materials of Examples 4-6 and Comparative Examples 1-6 were detected according to JC / T 313-2009 Expansion rate test method for expansive cement, and the results are shown in Table 2.

[0152] Table 2 Expansion rate test results

[0153] Type 7d expansion 28d expansion Example 4 (B1) 3.23％ 3.71％ Example 5 (B2) 3.92％ 4.31％ Example 6 (B3) 3.56％ 3.83％ Comparative Example 1 (S1) -0.31％ -0.54％ Comparative Example 2 (S2) -0.35％ -0.51％ Comparative Example 3 (E1) 1.33％ 2.03％ Comparative Example 4 (E2) 4.88％ 5.23％ Comparative Example 5 (E3) 0.28％ 0.37％ Comparative Example 6 (E4) 4.36％ 4.78％

[0154] From the above results, it can be seen that the full tailings cemented filling material prepared from the iron tailings powder-based cementitious material provided by the present application has good mechanical properties, the 7d compressive strength can reach 4.21MPa, which is 51.4% higher than that of the cement-based cemented filling material, and the 28d strength can reach 9.45MPa, which is 81.3% higher than that of the cement-based cemented filling material. And the 7d expansion rate of the full tailings cemented filling material prepared by the present application is 3.23%~3.92%, and the 28d expansion rate changes little compared with the 7d expansion rate, which can avoid the influence of late expansion on filling. The above results show that the full tailings cemented filling material provided by the present application can reach 100% expansion rate without adding expansion agent, which can effectively avoid multiple grouting and greatly save manpower and resources. The comprehensive experimental results of Examples 4-6 in terms of mechanical properties and expansion rate are better than those of the comparative examples.

[0155] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An iron ore tailings powder based cementitious material for full tailings cementation, characterized in that, The raw materials are as follows in parts by weight: 500-550 parts of iron tailing superfine powder, 300-350 parts of mineral powder, 20-30 parts of sulphate aluminate clinker, 100-120 parts of silicate cement clinker, 80-100 parts of desulfurization gypsum and 10-15 parts of methyl cellulose ether, wherein the D50 of the iron tailing superfine powder is less than or equal to 5 microns, the specific surface area is 900-1000 m 2 / kg, and contains 0.1%-0.3%wt of grinding aid, which is sodium hexametaphosphate, and the methyl cellulose ether is powdery, the specific surface area being 200-210 m 2 / kg.

2. The iron ore tailings powder based cementitious material for total tailings paste backfilling according to claim 1, characterized in that, The mineral components in the iron tailings superfine powder include quartz, potassium feldspar, sodium feldspar and biotite.

3. The iron ore tailings powder based cementitious material for total tailings paste backfilling according to claim 2, characterized in that, The content of quartz in the iron tailings superfine powder is 20wt%-25wt%, the content of potassium feldspar is 25wt%-35wt%, the content of sodium feldspar is 20wt%-30wt%, the content of biotite is 5wt%-10wt%, and the balance is other minerals.

4. The iron ore tailings powder based cementitious material for total tailings paste backfilling according to claim 1, characterized in that, The mineral powder is S95 grade mineral powder, and the specific surface area is 420-450 m 2 / kg; and / or The sulphate aluminate clinker meets the sulphate aluminate clinker standard GB / T37125-2018, the basicity coefficient is 0.9-1.0, and the aluminum-sulfur ratio is 3.5-4.0; and / or The portland cement clinker meets the portland cement clinker national standard GB / T21372-2008; and / or The D50 of the iron tailings superfine powder is 3-5μm.

5. The iron ore tailings powder based cementitious material for total tailings paste backfilling according to claim 1, characterized in that, The grinding aid is powdered sodium hexametaphosphate with a specific surface area of 200-230 m 2 / kg.

6. The process for the preparation of iron ore tailings powder based cementitious material for total tailings paste backfilling according to any one of claims 1 to 5, characterized in that, Specifically comprising the following steps: S1, drying the iron tailings powder and then adding the grinding aid to grind to obtain the iron tailings superfine powder; S2, mixing and grinding the sulphate aluminate clinker, the portland cement clinker and the methyl cellulose ether to obtain a cement clinker mixture; S3, uniformly mixing the iron tailings superfine powder with the cement clinker mixture, the mineral powder and the desulfurization gypsum to obtain the iron tailings powder-based cementitious material for full tailings cementation.

7. The production method according to claim 6, wherein The drying temperature in S1 is 100-105℃, and the moisture content is ≤1.5wt% after drying; and / or The grinding speed in S1 is 45-55r / min, and the grinding time is 150-180min; and / or The grinding speed in S2 is 45-55r / min, and the grinding time is 50-70min.

8. The application of the iron tailings powder-based cementitious material for full tailings cementation prepared by the preparation method of claim 6 or 7 in the preparation of full tailings cementation filling material.

9. A full tailings cemented fill material, characterised in that, The raw materials include: the iron tailings powder-based cementitious material for full tailings cementation prepared by the preparation method of claim 6 or 7, 180-200 parts by weight, water, 630-660 parts by weight, and metal tailings, 1200-1300 parts by weight.

10. The method of producing a full tailings cemented fill material as claimed in claim 9, characterized in that, Specifically comprising the following operation: uniformly mixing the iron tailings powder-based cementitious material, water and metal tailings to obtain the full tailings cementation filling material.

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