Pumping premixed concrete using mine solid waste as raw material and preparation method thereof

Abstract

The invention aims at solving the problems of complex process, high concrete cost, high carbon emission and the like in the prior art, and provides premixed concrete for pumping by taking mine solid waste as a raw material and a preparation method of the premixed concrete. The invention relates to premixed concrete for pumping by taking mine solid waste as a raw material. The premixed concrete consists of aggregate, a cementing material, water and an additive. The raw materials of a cementing material in the concrete are granulated blast-furnace slag and desulfurized fly ash and do not contain cement clinker, and the aggregate is iron tailing sand, barren rock machine-made sand and barren rock coarse aggregate. The problems of high cost and high carbon dioxide emission when the cement clinker is used as a cementing material are solved while a large amount of industrial solid wastes such as tailings and barren rocks are utilized. The concrete shows excellent working performance and mechanical property, can be applied to various engineering scenes such as road operation, mining filling materials and the like, and is a good substitute of cement concrete.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive utilization of solid waste resources and building materials technology, and particularly relates to a ready-mixed concrete for pumping using mining solid waste as raw materials and a preparation method thereof. Background Art

[0002] Ready-mixed pumped concrete is a concrete that is made of cementitious materials, aggregates, water, and admixtures added as needed, which are measured and mixed in a certain proportion at a centralized mixing station, and transported to the place of use by a concrete transport truck within a certain period of time. It is also called commercial concrete. Cement is a traditional cementitious material and is widely used in concrete structures, but it consumes a lot of energy and emits a lot of carbon. Iron tailings and waste rock are by-products of the iron ore mining and beneficiation process. Most of the tailings and waste rock are in a stockpile state, which brings serious environmental and safety problems. Therefore, the implementation of effective tailings and waste rock solid waste resource application technology is crucial to alleviate environmental problems and stockpiling. In concrete production, aggregates account for 75% of its volume. Therefore, using iron tailings and waste rock as concrete aggregates is an effective way to achieve large-scale consumption.

[0003] Currently, research on the preparation of ready-mixed concrete for pumping using solid waste-based cementitious materials and tailings and waste rock is also quite popular.

[0004] For example, CN 110627426 B discloses "A method for preparing green ultra-high performance concrete", which solves the problems of high cost and low waste slag utilization of existing ultra-high performance concrete. However, this patent uses three different crushing and grinding methods to process three different raw ores, which is a relatively complex process with high requirements for slurry concentration and raw ore properties. In addition, the wet grinding method used is extremely rare in the current industry, making industrial application difficult.

[0005] CN114477890A discloses "A kind of ultra-fine iron tailings sand concrete and its preparation method", which uses ultra-fine iron tailings sand to replace 40% of natural sand, so that the concrete mixture can meet the requirements of pumped concrete. The main raw material of the cementitious material of this invention is cement clinker, and tailings sand cannot replace natural sand 100%.

[0006] CN114409361A discloses "A kind of premixed pumpable concrete prepared from fly ash and its preparation method", which uses fly ash and desulfurized gypsum to prepare solid waste and cementitious materials, and mixes with 110-140 parts of cement, water, admixtures, machine-made fine aggregate and machine-made coarse aggregate to obtain pumpable concrete. This invention improves the utilization rate of industrial solid waste. However, the amount of cement used in this invention is relatively high, and the cost of concrete is not low.

[0007] CN111393105A discloses "A kind of fully machine-made sand high-strength super-high-rise pumping concrete and its production method and application". The aggregate used in the concrete is all machine-made sand, with a 28d compressive strength of more than 90MPa, which can achieve super-high-rise pumping. However, the cement content in the cementitious material of the invention is at least 56%, and the production cost of concrete may be further reduced. Summary of the invention

[0008] The purpose of the present invention is to provide a premixed concrete and its preparation method for pumping using mining solid waste as raw materials in order to solve the problems of complex process, high concrete cost and high carbon emissions in the prior art. The raw materials of the cementitious material in the concrete are granulated blast furnace slag and desulfurization ash, and do not contain cement clinker. The aggregates are iron tailings sand, waste rock machine-made sand and waste rock coarse aggregate. While making extensive use of industrial solid wastes such as tailings and waste rocks, the difficult problems of high cost and high carbon dioxide emissions of cement clinker as a cementitious material are solved. The concrete shows excellent working performance and mechanical properties, and can be applied to various engineering scenarios such as road operations and mining filling materials. It is a good substitute for cement concrete.

[0009] A ready-mixed concrete for pumping using mining solid waste as raw material, comprising aggregate, cementitious material, water and admixture;

[0010] Aggregates include, by weight: 140-160 parts of iron ore tailings sand, 550-650 parts of waste rock machine-made sand, and 900-1000 parts of waste rock coarse aggregate; cementitious materials include, by weight: 245-385 parts of granulated blast furnace slag powder, and 147-275 parts of desulfurized ash; water includes, by weight: 165-190 parts, and admixtures include water reducer and pumping agent, by weight: 2.8-3.8 parts.

[0011] Furthermore, in the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw material, the specific surface area of ​​the cementitious material is 500m 2 / kg~650m 2 / kg.

[0012] Furthermore, in the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw material, the slag powder in the cementitious material complies with the standard requirements of GB / T18046-2017 "Granulated blast furnace slag powder used in cement, mortar and concrete".

[0013] Furthermore, in the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw material, the desulfurization ash in the cementitious material is a by-product of flue gas desulfurization; the specification of the desulfurization ash is: particle size D90 is 30-40μm or specific surface area is 400-600m 2 / kg.

[0014] Furthermore, in the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw material, the iron tailings sand in the aggregate is the tailings of Anshan-type iron ore; preferably, the iron tailings sand has main mineral components such as quartz, chlorite, amphibole, etc., with a fineness modulus of 2.4 to 2.8 and an average particle size of <5 mm.

[0015] Furthermore, in the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw material, the waste rock machine-made sand in the aggregate is machine-made sand prepared by crushing waste rock in the mining process, and has a fineness modulus of 3.0 to 3.6.

[0016] Furthermore, in the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw material, the waste rock coarse aggregate in the aggregate is coarse aggregate prepared by crushing waste rock in the mining process, and has a particle size of 5 to 20 mm.

[0017] Furthermore, in the above-mentioned all-solid waste premixed pumpable concrete, the admixtures are polycarboxylate-based high-efficiency water reducing agent and sodium gluconate slump retaining agent.

[0018] The second technical solution of the present invention is that the method for preparing the above-mentioned ready-mixed concrete for pumping using mining solid waste as raw materials comprises the following steps:

[0019] Step 1: Mix slag powder and desulfurized ash by weight and grind to a specific surface area of ​​500m 2 / kg~650m 2 / kg of gelling material is obtained;

[0020] Step 2: uniformly mixing the cementitious material prepared in step 1 with the iron tailings sand, waste rock machine-made sand, and waste rock coarse aggregate according to corresponding weight portions to obtain a dry mix;

[0021] Step 3: Take corresponding weight portions of water and admixture and add them to the dry mix obtained in step 2, stir evenly, and obtain ready-mixed concrete for pumping.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The raw materials of cementitious materials in concrete are slag and desulfurized ash. By mixing and grinding, the active Al2O3 and active SiO2 in the particles are increased, the reaction contact area is increased, and the activity of the particles is improved. No cement clinker is required, the carbon emissions are low, and the production cost is greatly reduced.

[0024] (2) The aggregate in the concrete is made of machine-made sand and coarse aggregate made from iron tailings and waste rock, and does not contain river sand or sand and gravel produced by "rock blasting", which reduces production costs. Compared with other concretes, the amount of solid waste added to this concrete is greatly increased, which reduces the cost of aggregates and increases its commercial value.

[0025] (3) The concrete composition is simple, the preparation process is simple, the concrete production efficiency is high, and a higher utilization rate of industrial solid waste can be achieved. The entire process does not produce secondary pollution, avoids the problem of high carbon dioxide emissions, and achieves the goal of environmental protection and energy saving to the greatest extent.

[0026] (4) By utilizing the theory of multi-solid waste synergy, such as the rebonding of silicon (aluminum) oxygen bonds on the surface of tailings and waste rock and the alkaline environment provided by desulfurization ash, we can prepare all-solid waste concrete with good performance, greatly improve the utilization rate of desulfurization ash, tailings and waste rock, and reduce land occupation.

[0027] (5) The concrete of the present invention is a pumpable premixed concrete. In actual engineering, the good pumpability of the mixture is a prerequisite for the smooth implementation of pumping construction. Concrete raw materials and mix ratio are key factors for the smooth implementation of concrete operations. The present invention uses all solid waste as raw materials to make the concrete meet the performance requirements of pumpable premixed concrete under a reasonable mix ratio. DETAILED DESCRIPTION

[0028] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0029] The slag powder in the embodiment meets the requirements of GB / T18046-2017 "Granulated blast furnace slag powder for cement, mortar and concrete" standard; desulfurization ash is a by-product of flue gas desulfurization, and its specifications are: particle size D90 is 30-40μm or specific surface area is 400-600m 2 / kg; iron tailings sand is the tailings of Anshan-type iron ore, and its main mineral components include quartz, chlorite, amphibole, etc., with a fineness modulus of 2.4-2.8 and an average particle size of <5mm; waste rock machine-made sand is the machine-made sand prepared by crushing waste rock in the mining and selection process, with a fineness modulus of 3.0-3.6; waste rock coarse aggregate is the coarse aggregate prepared by crushing waste rock in the mining and selection process, with a particle size of 5-20mm; the admixtures are polycarboxylate-based high-efficiency water reducer and sodium gluconate slump retainer.

[0030] Example 1

[0031] A method for preparing ready-mixed concrete for pumping using mining solid waste as raw material:

[0032] 1. Preparation of cementitious materials

[0033] 1) Dry and grind the slag to a particle size of 40 μm (D90) or a specific surface area of ​​400 m 2 / kg;

[0034] 2) Dry and grind the desulfurized ash to a particle size D90 of 40 μm or a specific surface area of ​​400 m 2 / kg;

[0035] 3) Mix the above-mentioned materials in the ratio of 55 parts slag and 45 parts desulfurized ash and grind them to a specific surface area of ​​550m 2 / kg, and the gelling material is obtained;

[0036] 2. Preparation of ready-mixed pumped concrete

[0037] 1) mixing the cementitious material obtained in step 1 with the iron tailings sand, waste rock machine-made sand, and waste rock coarse aggregate in corresponding weight proportions to obtain a dry mix;

[0038] 2) adding corresponding weight portions of water and admixture to the dry mix obtained in step 1), stirring evenly to obtain premixed pumpable concrete.

[0039] Table 1 Concrete mix ratio data table (Concrete material consumption per cubic meter: kg / m 3 )

[0040]

[0041]

[0042] Table 2 Compressive strength of concrete at different ages in Example 1

[0043]

[0044] Table 3 Concrete slump and expansion of Example 1

[0045]

[0046] Example 2

[0047] A method for preparing ready-mixed concrete for pumping using mining solid waste as raw material:

[0048] 1. Preparation of cementitious materials

[0049] 1) Dry and grind the slag to a particle size of 35 μm (D90) or a specific surface area of ​​500 m 2 / kg;

[0050] 2) Dry and grind the desulfurized ash to a particle size D90 of 35 μm or a specific surface area of ​​500 m 2 / kg;

[0051] 3) The above-mentioned materials are uniformly mixed in the following proportions: 60 parts of slag and 40 parts of desulfurized ash are mixed and ground to a specific surface area of ​​550m 2 / kg, and the gelling material is obtained;

[0052] 2. Preparation of ready-mixed pumped concrete

[0053] 1) mixing the cementitious material obtained in step 1 with the iron tailings sand, waste rock machine-made sand, and waste rock coarse aggregate in corresponding parts by weight to obtain a dry mix;

[0054] 2) adding corresponding weight portions of water and admixture to the dry mix obtained in step 1), stirring evenly to obtain premixed pumpable concrete.

[0055] Table 4 Concrete mix ratio data table (Concrete material consumption per cubic meter: kg / m 3 )

[0056] Cementitious materials Iron tailings Waste rock machine-made sand Waste rock coarse aggregate water Admixtures 510 150 600 960 180 3.06

[0057] Table 5 Compressive strength of concrete at different ages in Example 2

[0058]

[0059]

[0060] Table 6 Concrete slump and expansion of Example 2

[0061]

[0062] Example 3

[0063] A method for preparing ready-mixed concrete for pumping using mining solid waste as raw material:

[0064] 1. Preparation of cementitious materials

[0065] 1) Dry and grind the slag to a particle size of 35 μm (D90) or a specific surface area of ​​500 m 2 / kg;

[0066] 2) Dry and grind the desulfurized ash to a particle size D90 of 35 μm or a specific surface area of ​​500 m 2 / kg;

[0067] 3) Mix the above mentioned materials in the following proportions: 65 parts of slag and 35 parts of desulfurized ash, grind to a specific surface area of ​​550m 2 / kg, and the gelling material is obtained;

[0068] 2. Preparation of ready-mixed pumped concrete

[0069] 1) mixing the cementitious material obtained in step 1 with the iron tailings sand, waste rock machine-made sand, and waste rock coarse aggregate in corresponding parts by weight to obtain a dry mix;

[0070] 2) adding corresponding weight portions of water and admixture to the dry mix obtained in step 1), stirring evenly to obtain premixed pumpable concrete.

[0071] Table 7 Concrete mix ratio data table (material consumption per cubic meter of concrete: kg / m 3 )

[0072] Cementitious materials Iron tailings Waste rock machine-made sand Waste rock coarse aggregate water Admixtures 550 160 560 940 190 3.74

[0073] Table 8 Compressive strength of concrete at different ages in Example 3

[0074]

[0075] Table 9 Example 3 Concrete slump and expansion

[0076]

[0077] Example 4

[0078] A method for preparing ready-mixed concrete for pumping using mining solid waste as raw material:

[0079] 1. Preparation of cementitious materials

[0080] 1) Dry and grind the slag to a particle size of 35 μm (D90) or a specific surface area of ​​500 m 2 / kg;

[0081] 2) Dry and grind the desulfurized ash to a particle size D90 of 35 μm or a specific surface area of ​​500 m 2 / kg;

[0082] 3) Mix the above mentioned materials in the following proportions: 70 parts of slag and 30 parts of desulfurized ash and grind them to a specific surface area of ​​550m 2 / kg, and the gelling material is obtained;

[0083] 2. Preparation of ready-mixed pumped concrete

[0084] 1) mixing the cementitious material obtained in step 1 with the iron tailings sand, waste rock machine-made sand, and waste rock coarse aggregate in corresponding parts by weight to obtain a dry mix;

[0085] 2) adding corresponding weight portions of water and admixture to the dry mix obtained in step 1), stirring evenly to obtain premixed pumpable concrete.

[0086] Table 10 Concrete mix ratio data table (material consumption per cubic meter of concrete: kg / m 3 )

[0087] Cementitious materials Iron tailings Waste rock machine-made sand Waste rock coarse aggregate water Admixtures 530 150 580 960 180 3.34

[0088] Table 11 Compressive strength of concrete at different ages in Example 4

[0089]

[0090] Table 12 Slump and expansion of concrete in Example 4

[0091]

[0092] It can be seen from the above tables that the pumped concrete prepared by the present invention has excellent compressive strength and can meet the strength requirements of different strength grades. Moreover, the concrete of the above embodiments did not have the phenomenon of stratification and segregation, nor did it appear sticky, and the concrete had good workability such as cohesiveness and water retention. According to GB / T14902-2019 "Ready-mixed Concrete Standard", the slump of the concrete mixture of each embodiment meets the grade requirements of S5 and the expansion meets the grade requirements of F5. In summary, the all-solid waste premixed pumped concrete of the present invention uses industrial solid waste and admixtures to prepare all-solid waste premixed pumped concrete, so that industrial solid waste is maximized. Through design experiments, the optimal dosage of cementitious materials and aggregates in the all-solid waste cementitious system is provided, so as to solve the problem of industrial solid waste reduction, harmlessness and resource utilization, promote the coordinated utilization of solid waste and environmental protection, and lay the foundation for engineering application for large-scale replacement of cement solidification stabilization safe landfill, preliminary combination of cementitious filling mining technology or preparation of building concrete.

[0093] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A ready-mixed concrete for pumping using mining solid waste as raw materials, comprising aggregate, cementitious material, water and admixture, characterized in that: Aggregates include, by weight: 140-160 parts of iron ore tailings sand, 550-650 parts of waste rock machine-made sand, and 900-1000 parts of waste rock coarse aggregate; cementitious materials include, by weight: 245-385 parts of granulated blast furnace slag powder, and 147-275 parts of desulfurized ash; water includes, by weight: 165-190 parts, and admixtures include water reducer and pumping agent, by weight: 2.8-3.8 parts.

2. The ready-mixed concrete for pumping using mining solid waste as raw materials according to claim 1, characterized in that: The specific surface area of ​​the gelling material is 500m 2 / kg~650m 2 / kg.

3. The ready-mixed concrete for pumping using mining solid waste as raw materials according to claim 1, characterized in that: The granulated blast furnace slag powder meets the requirements of GB / T18046-2017 "Granulated blast furnace slag powder for cement, mortar and concrete".

4. The ready-mixed concrete for pumping using mining solid waste as raw materials according to claim 1, characterized in that: The desulfurized ash is a byproduct of flue gas desulfurization, with a particle size D90 of 30-40 μm or a specific surface area of ​​400-600 m 2 / kg.

5. The ready-mixed concrete for pumping using mining solid waste as raw material according to claim 1, characterized in that: The iron tailings sand is the tailings of Anshan-type iron ore, with a fineness modulus of 2.4 to 2.8 and an average particle size of <5 mm.

6. The ready-mixed concrete for pumping using mining solid waste as raw material according to claim 1, characterized in that: The waste rock machine-made sand is machine-made sand prepared by crushing waste rock in the ore mining and selection process, and has a fineness modulus of 3.0 to 3.

6.

7. The ready-mixed concrete for pumping using mining solid waste as raw materials according to claim 1, characterized in that: The waste rock coarse aggregate is coarse aggregate prepared by crushing waste rock in the ore mining process, and has a particle size of 5 to 20 mm.

8. The ready-mixed concrete for pumping using mining solid waste as raw materials according to claim 1, characterized in that: The admixtures are polycarboxylate-based high-efficiency water reducing agent and sodium gluconate collapse retaining agent.

9. The method for preparing ready-mixed concrete for pumping using mining solid waste as raw materials according to claim 1, characterized in that: The steps include: Step 1: Mix slag powder and desulfurized ash in proportion by weight and grind to a specific surface area of ​​500m 2 / kg~650m 2 / kg of gelling material is obtained; Step 2: uniformly mixing the cementitious material prepared in step 1 with the iron tailings sand, waste rock machine-made sand, and waste rock coarse aggregate in corresponding weight proportions to obtain a dry mix; Step 3: Add water and admixture in corresponding weight proportions to the dry mix obtained in step 2, stir evenly, and obtain ready-mixed concrete for pumping.

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