Commercial concrete cement and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of cement for commercial concrete, and particularly relates to commercial concrete cement and a preparation method thereof. In order to solve the problems of short hardening time, large bleeding, poor fluidity and the like of concrete prepared from existing cement, the invention provides commercial concrete cement which is prepared from the following components in percentage by mass: 81.0% + / -1% of limestone I, 6.5% + / -0.5% of sandstone, 6.5% + / -0.5% of aluminum ore waste rock, 2.0% + / -0.5% of coal gangue, 0.5% + / -0.3% of copper slag and the balance of water. 1.5 + / -0.3% of phosphorus slag, 1.0 + / -0.3% of phosphogypsum I and 1.0 + / -0.3% of copper slag are used as raw materials and are subjected to powder grinding, homogenization, clinker calcination and cement powder grinding to obtain the cement. The commercial concrete cement prepared by the invention is proper in setting time and convenient to adjust, and the prepared concrete is long in plasticity retaining property, good in fluidity, small in slump gradual loss and more suitable for long-distance or long-time transportation.

Description

Technical Field

[0001] The present invention belongs to the technical field of cement preparation for commercial concrete, and particularly relates to commercial concrete cement and its preparation method. Background Art

[0002] Commercial concrete, also known as ready-mixed concrete, refers to pre-mixed concrete mixtures with qualified quality, which are sold to construction units in the form of commodities and transported to the construction site for pouring. It realizes the centralization, specialization, and commercialization of the concrete production process and is usually used in concrete structures in construction and infrastructure projects. It is an important part of infrastructure construction, such as roads, bridges, and water conservancy projects. As the main raw material of commercial concrete, cement is an important source of concrete quality. Currently, ordinary P·O42.5R cement is mainly used for commercial concrete in China. However, due to the long-term constraint of traditional usage concepts, the widely circulated ordinary P·O42.5R cement on the market is mainly suitable for the civil market or on-site mixing at the construction site. Therefore, the concrete prepared with it generally has many problems when applied to commercial concrete, such as short hardening time, large bleeding, poor fluidity, large slump loss over time, narrow aggregate adaptation range, and high admixture dosage. In addition, with the rapid development of urban construction, on-site mixing of concrete not only has a low rate but also does not meet the environmental protection requirements. Therefore, using commercial concrete for construction has become the current mainstream method. Therefore, there is an urgent need to invent a cement specifically suitable for use in commercial concrete mixing plants for long-distance or long-time transportation. Summary of the Invention

[0003] In order to overcome the technical problems such as short hardening time, large bleeding, poor fluidity, large slump loss over time, narrow aggregate adaptation range, and high admixture dosage of the concrete prepared with conventional cement on the market, the present invention provides a commercial concrete cement and its preparation method. The setting time of this cement is appropriate and easy to adjust. The prepared concrete has a long plastic retention time, good fluidity, small slump loss over time, a wide range of adaptation to concrete aggregates, a lower admixture dosage under the same conditions, is more suitable for long-distance or long-time transportation, can significantly improve the performance of the prepared concrete, greatly reduce the production cost of commercial concrete, overcome the problem of ultra-long plastic retention of fresh concrete, and effectively solve the problem of deterioration of plasticity and construction performance after long-distance or long-time transportation. At the same time, the production of this cement can also reduce the enterprise's greenhouse gas emissions and achieve low-carbon and green production.

[0004] To achieve the above application objectives, the technical solutions adopted in this application are as follows:

[0005] In a first aspect, the present invention provides a commercial concrete cement, which is prepared by raw material grinding, homogenization, clinker calcination, and cement grinding using limestone I, sandstone, aluminum ore waste, coal gangue, copper slag, phosphorus slag, phosphogypsum I, and copper slag as raw materials; wherein, by mass percentage, in the raw meal, limestone I is 81.0% ± 1%, sandstone is 6.5% ± 0.5%, aluminum ore waste is 6.5% ± 0.5%, coal gangue is 2.0% ± 0.5%, copper slag is 0.5% ± 0.3%, phosphorus slag is 1.5 ± 0.3%, phosphogypsum I is 1.0 ± 0.3%, and copper slag is 1.0 ± 0.3%.

[0006] Further, by mass percentage, the above raw material indexes satisfy at least one of the following:

[0007] Limestone I: CaO ≥ 50.00%, MgO ≤ 2.50%, total sulfur ≤ 0.15%, moisture ≤ 2.0%, R2O ≤ 0.12%;

[0008] Sandstone: 80.0% ≤ SiO2 ≤ 85.0%, R2O ≤ 2.20%, moisture ≤ 16.0%;

[0009] Aluminum ore waste: 22.0% ≤ Al2O3 ≤ 30.0%, R2O ≤ 1.50%, total chromium ≤ 240 mg / kg, radionuclide limit Ira, Ir ≤ 0.8, moisture ≤ 10.0%;

[0010] Coal gangue: Al2O3 ≥ 18.0%, R2O ≤ 2.50%, moisture ≤ 8.0%;

[0011] Copper slag: Fe2O3 ≥ 48.0%, R2O ≤ 1.50%, moisture ≤ 4.0%;

[0012] Phosphorus slag: CaO ≥ 42%, MgO ≤ 6%, 2.0% ≤ P2O5 ≤ 5.0%, moisture ≤ 12.0%, R2O ≤ 1.50%;

[0013] Phosphogypsum I: crystal water ≥ 16.00%, CaCO3 ≤ 0, MgCO3 ≤ 0, moisture ≤ 12.0%, Loss ≤ 18.00%, SO3 ≥ 38.00%, P2O5 ≤ 0.80%;

[0014] Copper slag: Fe2O3 ≥ 50.0%, R2O ≤ 1.50%, moisture ≤ 10.0%.

[0015] Further, in the cement grinding, by mass percentage, the clinker is 75.92% ± 1.0%, phosphogypsum II is 6.0% ± 0.5%, fly ash is 1.5% ± 0.5%, granulated blast furnace slag is 12.0% ± 0.5%, limestone II is 4.5 ± 0.5%, and the special grinding aid is 0.08% ± 0.02%.

[0016] Furthermore, by mass percentage, the above raw material indicators meet at least one of the following:

[0017] Phosphogypsum II: Crystal water ≥ 16.00%, total moisture ≤ 12.0%, Loss ≤ 18.00%, SO3 ≥ 38.00%, P2O5 ≤ 0.80%, chloride ion ≤ 0.5%, pH value ≥ 8.0, radionuclide limit I Ra 、I r ≤ 0.9;

[0018] Fly ash: Loss ≤ 6.0%, water content ≤ 0.8%, SO3 ≤ 3.0%, f-CaO ≤ 2.0%, combined content of SiO2 + Al2O3 + Fe2O3 ≥ 70.0%, density ≤ 2.5 g / cm 3 , soundness is qualified, CaSO3﹒1 / 2H2O ≤ 2.5%, ammonium ion content ≤ 180 mg / kg, radionuclide limit I Ra 、I r ≤ 0.9, R2O ≤ 2.0%;

[0019] Granulated blast furnace slag: mass coefficient ≥ 1.3, TiO2 ≤ 9.6%, MnO ≤ 9.6%, F ≤ 1.8%, sulfide ≤ 2.5%, bulk density ≤ 1.1×10 3 Kg / m 2 , maximum particle size ≤ 40 mm, particles larger than 10 mm ≤ 6.0%, vitreous content ≥ 75%, radionuclide limit I Ra 、I r ≤ 0.8, water-soluble chromium (VI) ≤ 8.0 mg / kg;

[0020] Limestone II: CaO ≥ 50.00%, MgO ≤ 3.00%, residue on 50 mm sieve ≤ 15.0%, methylene blue value ≤ 1.1 g / kg, radionuclide limit I Ra 、I r ≤ 0.8, water-soluble chromium (VI) ≤ 8.0 mg / kg;

[0021] Special grinding aid: Grace ES5869, containing components with retarding and slump retention effects. The difference in solid content, density, and pH value between two adjacent batches of grinding aids of the same model does not exceed 2.0, 0.03, and 1.0 respectively.

[0022] Furthermore, the coal consumption is 7.0 - 9.0% of the raw meal consumption, and the ratio of the usage amount of head and tail coal is 3:7.

[0023] Preferably, the coal consumption is 8.2% of the raw meal consumption, and the ratio of the usage amount of head and tail coal is 3:7.

[0024] Furthermore, the coal combustion indexes include: 18% ≤ Vad ≤ 32%, Qnet,ad ≥ 22781 J / g, R2O ≤ 2.50%, total sulfur ≤ 1.80%, Mt ≤ 13.0%.

[0025] Furthermore, the as-ground quality indexes of the commercial concrete cement include: specific surface area 370 ± 10 m 2 / Kg, and the fineness of residue on 45um sieve is 8.0% ± 1%.

[0026] Furthermore, the factory quality indexes of the commercial concrete cement include: initial setting time 200 - 230 min, final setting time 260 - 290 min, the time-dependent loss after 1 hour ≥ -80 mm and ≤ 10 mm, and the 28-day compressive strength 53.0 MPa ± 2.0 MPa.

[0027] In the second aspect, the present invention provides a method for preparing the above-mentioned commercial concrete cement, comprising the following steps:

[0028] S1. Grinding and homogenizing raw materials including limestone I, sandstone, waste aluminum ore, coal gangue, copper slag, phosphorus slag, phosphogypsum I and copper slag;

[0029] S2. Pre-decomposing the homogenized raw materials and calcining them into clinker;

[0030] S3. Cooling and homogenizing the clinker, and then co-grinding it with phosphogypsum II, fly ash, granulated blast furnace slag, limestone II and special grinding aid into cement.

[0031] Furthermore, in step S1, control the lime saturation coefficient KH of the homogenized raw materials: 0.950 ± 0.020, silica modulus SM: 2.35 ± 0.10, and alumina modulus IM: 1.50 ± 0.10.

[0032] Furthermore, in step S2, control the lime saturation coefficient KH of the calcined clinker: 0.910 ± 0.020, silica modulus SM: 2.35 ± 0.10, and alumina modulus IM: 1.50 ± 0.10.

[0033] Furthermore, in step S2, the calcination temperature is 1420 ± 30 °C, oxygen content > 1.5%, and internal and external air pressures > 55 kPa.

[0034] Furthermore, in step S3, the cooling temperature of the clinker is 65 °C lower than room temperature.

[0035] Furthermore, in step S3, control the grinding fineness to a specific surface area of 370 ± 10 m 2 / kg, the fineness of residue on 45um sieve is 8.0% ± 1%, and the comprehensive moisture content entering the mill < 1%.

[0036] Beneficial effects: In the existing raw meal of ordinary P·O42.5R cement, the present invention adds low-grade raw materials such as coal gangue and non-carbonate substitute raw materials (phosphorus slag, phosphogypsum I and copper slag), and by optimizing the component ratios of various raw materials in the raw meal, the carbon emission in the clinker production process is reduced by 2.4%; at the same time, in the cement production process, the environmental protection material phosphogypsum is used as a setting retarder and a special grinding aid, and the ratios of the clinker, the setting retarder and the grinding aid are optimized. The commercial concrete cement prepared not only meets the requirements of GB175-2023, but also compared with the existing ordinary P·O42.5R cement, its initial setting time is significantly extended from 168 min to 227 min, and at 28 days, the compressive strength is increased by 3.3 MPa and the fluidity is better; after being prepared into concrete, the slump loss of the concrete over time is small, the fluidity change is small, and the strength is as high as more than 40 MPa after 28 days. It can be seen that the commercial concrete cement prepared by the present invention has a suitable setting time and is convenient to adjust. The prepared concrete has a long plastic retention time, good fluidity, small slump loss over time, a wide adaptability range for concrete aggregates, a lower admixture dosage under the same conditions, and is more suitable for long-distance or long-time transportation. Detailed implementation manners

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below in conjunction with the implementation manners. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those of ordinary skill in the art.

[0038] In an implementation manner of the present invention, first, a commercial concrete cement is provided, which is prepared by raw meal grinding, homogenization, clinker calcination and cement grinding using limestone I, sandstone, aluminum ore waste, coal gangue, copper ore slag, phosphorus slag, phosphogypsum I and copper slag as raw materials; wherein, by mass percentage, in the raw meal, limestone I is 81.0% ± 1%, sandstone is 6.5% ± 0.5%, aluminum ore waste is 6.5% ± 0.5%, coal gangue is 2.0% ± 0.5%, copper ore slag is 0.5% ± 0.3%, phosphorus slag is 1.5 ± 0.3%, phosphogypsum I is 1.0 ± 0.3%, and copper slag is 1.0 ± 0.3%.

[0039] Among them, coal gangue can reduce the usage amount of aluminum ore waste as an aluminous correction raw material. Coupled with a certain amount of heat contained in coal gangue, it can effectively reduce coal consumption. However, the alkali and sulfur contents of coal gangue are relatively high, and the ratio of coal gangue needs to be reasonably controlled. Otherwise, process accidents such as preheater coating and material blockage and excessive sulfide emissions will occur. The appropriate dosage and mixing ratio of coal gangue should be determined in combination with other raw materials to ensure that the use of coal gangue can not only meet the production requirements but also will not cause adverse process changes.

[0040] Using non-carbonate alternative raw materials in clinker production can significantly reduce greenhouse gas emissions. Therefore, introducing non-carbonate alternative raw materials can achieve the process emissions of the clinker production line. Since the control of trace elements is particularly important after introducing non-carbonate alternative raw materials such as phosphorus slag, copper slag, and phosphogypsum. Especially, phosphorus pentoxide in phosphorus slag and phosphogypsum can reduce the firing temperature by 50 °C. However, if it cannot be completely dissolved into C3S, it will cause the setting time of the clinker to be prolonged, the strength to be reduced, and agglomeration and large rings to occur in the rotary kiln during production. Therefore, it is necessary to determine the optimal dosage of phosphorus slag and phosphogypsum in combination with other raw materials.

[0041] Therefore, through research, the present invention finds that by controlling the components in the raw meal as follows, the produced cement has the best performance: limestone I 81.0% ± 1%, sandstone 6.5% ± 0.5%, aluminum ore waste rock 6.5% ± 0.5%, coal gangue 2.0% ± 0.5%, copper slag 0.5% ± 0.3%, phosphorus slag 1.5 ± 0.3%, phosphogypsum I 1.0 ± 0.3%, copper slag 1.0 ± 0.3%.

[0042] Further, in an embodiment of the present invention, in cement grinding, by mass percentage, clinker is 75.92% ± 1.0%, phosphogypsum II is 6.0% ± 0.5%, fly ash is 1.5% ± 0.5%, granulated blast furnace slag is 12.0% ± 0.5%, limestone II is 4.5 ± 0.5%, and special grinding aid is 0.08% ± 0.02%.

[0043] The present invention uses a special grinding aid (Grace ES5869). Compared with conventional grinding aids on the market, it uniquely introduces components with retarding and slump retention effects. At this dosage, the retarding of cement and the slump retention of concrete are achieved.

[0044] In another embodiment of the present invention, a method for preparing the above commercial concrete cement is also provided, including the following steps:

[0045] S1. Grind and homogenize the raw materials of limestone I, sandstone, aluminum ore waste rock, coal gangue, copper slag, phosphorus slag, phosphogypsum I, and copper slag.

[0046] S2. Pre-decompose and calcine the homogenized raw meal into clinker.

[0047] S3. After cooling and homogenizing the clinker, co-grind it with phosphogypsum II, fly ash, granulated blast furnace slag, limestone II, and special grinding aid into cement.

[0048] In a preferred embodiment of the present invention, in step S1, pre-homogenization is required before raw meal grinding to significantly reduce the amplitude of composition fluctuations and reduce its standard deviation, thereby facilitating the improvement of the uniformity of raw meal composition and stabilizing the thermal regime during clinker calcination.

[0049] In a preferred embodiment of the present invention, after homogenizing the raw meal, three rates are controlled, namely, the lime saturation coefficient KH of the raw meal: 0.950 ± 0.020, the silica modulus SM: 2.35 ± 0.10, and the alumina modulus IM: 1.50 ± 0.10. Controlling the three rates of the raw meal within this range can ensure the quality of the clinker, and when the apparent decomposition rate of the precalciner reaches 90.0 ± 1.0%, the decomposition of calcium carbonate in the raw meal is ensured, and the premature appearance of the liquid phase is avoided.

[0050] In a preferred embodiment of the present invention, the three rates of the clinker are controlled as follows: the lime saturation coefficient KH: 0.910 ± 0.020, the silica modulus SM: 2.35 ± 0.10, and the alumina modulus IM: 1.50 ± 0.10. Within this range, the burnability and strength of the calcined clinker can be improved, and the normal production process can be ensured.

[0051] In a preferred embodiment of the present invention, in step S3, the quality management method of "special grinding and special storage" is implemented, and the key points of control are the cement out of the mill and the cement leaving the factory, as shown in Table 1 - Table 2.

[0052] (1) Cement out of the mill: fineness, specific surface area and composition.

[0053] Table 1 Key points and indicators for quality control of cement out of the mill

[0054]

[0055] (2) Cement leaving the factory: including: Loss, MgO, R2O, SO3, chloride ion, fineness, soundness, cement composition, setting time, strength, etc.

[0056] Table 2 Key points and indicators for quality control of cement leaving the factory

[0057]

[0058]

[0059] In a preferred embodiment of the present invention, the coal consumption is 7.0 - 9.0% of the raw meal consumption, and the proportion of the head and tail coal consumption is 3:7; more preferably, the coal consumption is 8.2% of the raw meal consumption, and the proportion of the head and tail coal consumption is 3:7.

[0060] In a preferred embodiment of the present invention, the application index innovatively introduces the net paste fluidity value and the loss difference value for characterization, and quantifies the control index. On the premise of using the same admixture and the same dosage, the net paste fluidity value of the cement with the admixture is not less than that of the blank cement, and the 1h loss difference: cement with the admixture - blank cement ≤ 60mm.

[0061] In a preferred embodiment of the present invention, a semi-finished grinding system is selected for grinding, which includes a roller press + a dynamic separator + a ball mill + an O-SEPA separator. The entire grinding system is controlled according to this process, and the grinding efficiency can reach 80%, the grinding power consumption is less than 21 kwh / t, achieving the optimal power and the lowest energy consumption.

[0062] Specific embodiments will be listed below to explain the solution of the present invention. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified as to the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0063] Unless otherwise specified, the ratios in the following embodiments are all mass ratios.

[0064] Unless otherwise stated, the operating steps and parameters used in the examples and comparative examples are the same.

[0065] Example 1: Preparation of commercial concrete cement

[0066] 1. Raw materials

[0067] There are 10 kinds of raw materials used in the embodiments of the present invention, namely calcareous raw materials, siliceous raw materials, aluminous corrective raw materials, ferrous corrective raw materials, non-carbonate substitute raw materials, fuels, setting regulators, main admixtures, substitute admixtures and grinding aids. The types and quality requirements of the raw materials are shown in Table 3.

[0068] 1.1 Quality requirements

[0069] Table 3 Types and quality requirements of raw materials

[0070]

[0071] 1.2 Application index requirements

[0072] Characterized by the net paste fluidity value and the loss difference value. On the premise of using the same admixture and the same dosage, the net paste fluidity value of the cement with additive is not less than that of the blank cement, and the 1-hour loss difference: cement with additive - blank cement ≤ 60 mm.

[0073] Note: The cement with additive refers to the cement produced by adding a special grinding aid, and vice versa is the blank cement.

[0074] 2. Cement preparation steps

[0075] Limestone I, sandstone, waste aluminum ore, coal gangue, copper slag, phosphorus slag, phosphogypsum I, and copper slag are prepared into raw meal, then co - calcined with blended coal in a rotary kiln to form clinker, and finally ground together with phosphogypsum II, fly ash, granulated blast - furnace slag, limestone II, and special grinding aids to produce cement. The specific ratios of the examples and comparative examples are shown in Table 4 in detail.

[0076] Table 4 Mass ratio of cement raw materials / %

[0077]

[0078] 2.1 Raw meal preparation

[0079] 2.1.1 Crushing

[0080] The raw materials 1 - 5 in Table 3, namely limestone I, sandstone, waste aluminum ore, coal gangue, copper slag, phosphorus slag, and phosphogypsum I, are crushed respectively on a counter - attack crusher, and the crushing particle size ≤ 50 mm.

[0081] Since the particle size of copper slag < 50 mm, it does not need to be crushed separately.

[0082] 2.1.2 Pre - homogenization

[0083] The crushed limestone I, sandstone, waste aluminum ore, coal gangue, copper slag, phosphorus slag, phosphogypsum I, and copper slag are transported by belt and enter their respective independent rectangular pre - homogenization stockpilesheds. Pre - homogenization technology is used for homogenization, so that the raw materials with large composition fluctuations before storage become relatively uniform raw materials when taken out. The purpose of homogenization is to eliminate the long - cycle fluctuations in the composition of the incoming raw fuels, shorten the fluctuation cycle of the raw fuel composition, and provide good conditions for accurate batching, heat - matching, and raw meal grinding feeding. The specific pre - homogenization method is to use a side - type cantilever stacker for stacking and a bridge - type scraper reclaimer for reclaiming. After homogenization by the above method, the amplitude of composition fluctuations is significantly reduced, and its standard deviation is decreased, which is beneficial to improving the uniformity of raw meal composition and stabilizing the thermal regime during clinker calcination.

[0084] 2.1.3 Ratio and grinding

[0085] The pre - homogenized limestone I, sandstone, waste aluminum ore, coal gangue, copper slag, phosphorus slag, phosphogypsum I, and copper slag enter their respective batching bins, and then the limestone I, sandstone, waste aluminum ore, coal gangue, copper slag, phosphorus slag, phosphogypsum I, and copper slag are fed and mixed in proportion according to Table 4, and ground in a vertical mill. The grinding fineness is controlled so that the residue percentage on a 80 - um square - hole sieve is less than 16 ± 2. Under this parameter control, it is most conducive to the formation of minerals during high - temperature calcination of raw meal and has low power consumption.

[0086] 2.1.4 Homogenization

[0087] The qualified raw meal is conveyed to the raw meal homogenizing silo, where radial mixing and homogenization are carried out by means of air agitation and gravity technology. Its main technological feature is to make the raw meal homogenization operation continuous, that is, while the raw meal with large chemical composition fluctuations from the mill enters the silo, the raw meal with uniform composition can be continuously discharged from the bottom or side of the silo for use in the kiln. Stabilizing the composition of the raw meal entering the kiln is the prerequisite for stabilizing the thermal process system of clinker burning. The homogenization effect is judged based on the raw meal composition. The three modulus values of the raw meal are shown in Table 5 for details.

[0088] 2.2 Clinker Calcination

[0089] 2.2.1 Pulverized Coal Preparation

[0090] The blended coal is crushed and then ground by a vertical coal mill. The grinding fineness is controlled so that the residue percentage on a 80um square hole sieve is less than 4%. The qualified pulverized coal is stored in the head coal bin and the tail coal bin respectively. The pulverized coal in the head coal bin is sent to the rotary kiln for combustion through a coal injection pipe, and the pulverized coal in the tail coal bin is provided for combustion in the decomposition furnace. The coal consumption is 8.2% of the raw meal consumption, and the usage ratio of the head coal to the tail coal is 3:7.

[0091] 2.2.2 Raw Meal Pre-Decarbonation

[0092] The homogenized raw meal enters the suspension preheater for drying and dehydration of clay minerals. After dehydration, it enters the decomposition furnace. In the decomposition furnace, it is mixed with pulverized coal and rapidly absorbs the heat of fuel combustion in a suspended state, causing the calcium carbonate in the raw meal to rapidly decompose into calcium oxide. The temperature at the outlet of the decomposition furnace is controlled at 860℃ - 880℃, and the apparent decarbonation rate of the raw meal entering the kiln is 90.0 ± 1.0% as the judgment index to ensure the decomposition of calcium carbonate in the raw meal and avoid the premature appearance of liquid phase.

[0093] 2.2.3 Clinker Burning

[0094] The materials decomposed in the decomposition furnace enter the rotary kiln. With the help of the centrifugal force generated by the rotation of the rotary kiln and the wind force of the blower, they pass through the high-temperature area formed by the combustion of the pulverized coal ejected from the tail coal bin and are fired into clinker. The calcination temperature is controlled at 1420℃ to ensure sufficient combustion of the head coal, with the oxygen content in the kiln > 1.5%, and to ensure that the air pressure inside and outside the coal injection pipe > 55kPa, without generating a reducing atmosphere. The temperature in the burning zone is concentrated, the flame force is large, and the generation of fly ash materials is avoided.

[0095] The control range of the three modulus values of the clinker is shown in Table 5 for details.

[0096] Table 5 The three modulus values of raw meal and clinker

[0097]

[0098] 2.2.4 Clinker Cooling

[0099] The high-temperature clinker falling from the kiln head of the rotary kiln is cooled in the grate cooler. The temperature of the clinker leaving the grate cooler should be controlled below the ambient temperature + 65°C. Otherwise, it will cause the dehydration of phosphogypsum in the cement mill, and the cement adaptability will deteriorate.

[0100] 2.2.4 Clinker homogenization

[0101] After coming out of the grate cooler, the clinker enters the clinker silo for natural falling homogenization.

[0102] 2.3 Cement grinding

[0103] The above-mentioned homogenized clinker is ground together with industrial phosphogypsum II, fly ash, granulated blast furnace slag, limestone II and special grinding aids into cement. The production is divided into three stages, namely raw material homogenization, raw material grinding and cement homogenization. The cement grinding system used is Center drive closed-circuit grinding production.

[0104] 2.3.1 Raw material crushing

[0105] The clinker produced in the first stage is crushed on the crusher at the end of the cooler (also known as: grate cooler), and the crushing particle size ≤ 50mm. Among them, the inlet temperature of the clinker is lower than 150°C.

[0106] The setting regulator (industrial phosphogypsum) phosphogypsum II and limestone II are respectively crushed on the impact crusher, and the crushing particle size ≤ 50mm.

[0107] Fly ash and granulated blast furnace slag do not need to be crushed anymore due to their small particle sizes.

[0108] 2.3.2 Raw material pre-homogenization

[0109] The special clinker after crushing is homogenized in the homogenization silo, and phosphogypsum II, granulated blast furnace slag and limestone II are homogenized by pre-homogenization technology in the pre-homogenization storage shed, and fly ash is homogenized in the round steel silo to eliminate the periodic fluctuations of the raw material components of different batches entering the factory, make the raw material components uniform, and provide good conditions for accurate batching.

[0110] 2.3.3 Grinding

[0111] The semi-finished grinding system is selected for grinding, including a roller press + dynamic separator + ball mill + O-SEPA separator. The entire grinding system is controlled according to the following process, and the grinding efficiency can reach 80%, the grinding power consumption is less than 21 kwh / t, achieving the optimal power and the lowest energy consumption.

[0112] ① Ratio

[0113] After homogenization, it is transported by belt and enters respective independent batching bins, where the specially homogenized clinker, phosphogypsum II, fly ash, granulated blast furnace slag and limestone II are mixed according to the batching ratio in Table 4. The fineness of grinding is controlled with a specific surface area of 370±10m 2 / kg, and the residue fineness on a 45um sieve is 8.0%±1%. The comprehensive moisture content entering the mill is <1%.

[0114] ② Roller press grinding

[0115] The evenly mixed raw materials are transported to the roller press for the first pre-grinding, and the current of the roller press is stabilized at 60A.

[0116] ③ Dynamic classifier

[0117] The materials after roller press grinding are selected for finished products and semi-finished products through a dynamic classifier. The fine powder meeting the requirements directly enters the finished product bin, and the coarse powder not meeting the finished product requirements enters the ball mill for further grinding and does not return to the roller press. The rotational speed is fixed at 25Hz and the air volume is adjusted.

[0118] ④ Ball mill grinding

[0119] The coarse powder not meeting the finished product requirements is selected by the dynamic classifier and enters the ball mill for grinding. Ceramic balls are used as grinding media in the ball mill. The current of the mill is controlled at 120A±2A, the rotational speed of the tail fan of the mill is controlled at 31Hz±1Hz, and the lifting current at the mill outlet is controlled at 125A±5A.

[0120] ⑤ O-SEPA classification

[0121] After grinding by the ball mill, the O-SEPA classifier is used for classification. The powder meeting the requirements enters the finished product bin, and the materials not meeting the requirements return to the ball mill for further grinding. The air volume is fixed at 37Hz and the rotational speed is adjusted.

[0122] 2.3.4 Homogenization

[0123] A cooling system is configured to ensure that the temperature of the cement entering the warehouse is below 80°C.

[0124] 2.3.5 Production process

[0125] The production process control of the commercial concrete cement of the present invention implements a quality management method of "special grinding and special warehouse", and the key points of control are the cement out of the mill and the cement leaving the factory, as shown in Table 1 - Table 2.

[0126] 3. Cement advantages

[0127] The physical and chemical properties of the commercial concrete cement produced according to the above requirements, and the workability after being prepared into concrete are shown in Table 6 and Table 7 respectively. It can be seen from Table 6 and Table 7 that the commercial concrete cement prepared by the present invention not only meets the requirements of GB175-2023 "Common Portland Cement", but also has a suitable cement setting time and is convenient to adjust. The prepared concrete has a long plastic retention time, good fluidity, small slump loss over time, a wide range of adaptability to concrete aggregates, a lower admixture dosage under the same conditions, and is more suitable for long-distance or long-time transportation.

[0128] Table 6 Comparison of Product Advantages (Physical and Chemical Properties)

[0129]

[0130] Table 7 Comparison of Product Advantages (Workability of Concrete)

[0131]

[0132] Note: The admixture refers to a raw material when the cement is made into concrete. The type of admixture used in Table 7 is Huaxi HLP.

Claims

1. Commercial concrete cement, characterized in that: It is prepared from limestone I, sandstone, aluminum ore waste rock, coal gangue, copper slag, phosphorus slag, phosphogypsum I and copper slag through raw material grinding, homogenization, clinker calcination, and cement grinding; Among them, by mass percentage, in the raw material, limestone I is 81.0% ± 1%, sandstone is 6.5% ± 0.5%, aluminum ore waste rock is 6.5% ± 0.5%, coal gangue is 2.0% ± 0.5%, copper slag is 0.5% ± 0.3%, phosphorus slag is 1.5 ± 0.3%, phosphogypsum I is 1.0 ± 0.3%, and copper slag is 1.0 ± 0.3%.

2. The commercial concrete cement according to claim 1, wherein: By mass percentage, the raw material indexes meet at least one of the following: Limestone I: CaO ≥ 50.00%, MgO ≤ 2.50%, total sulfur ≤ 0.15%, moisture ≤ 2.0%, R2O ≤ 0.12%; Sandstone: 80.0% ≤ SiO2 ≤ 85.0%, R2O ≤ 2.20%, moisture ≤ 16.0%; Bauxite waste rock: 22.0% ≤ Al2O3 ≤ 30.0%, R2O ≤ 1.50%, total chromium ≤ 240 mg / kg, radionuclide limit I ra 、I r ≤ 0.8, moisture content ≤ 10.0%; Coal gangue: Al2O3 ≥ 18.0%, R2O ≤ 2.50%, moisture ≤ 8.0%; Copper slag: Fe2O3 ≥ 48.0%, R2O ≤ 1.50%, moisture ≤ 4.0%; Phosphorus slag: CaO ≥ 42%, MgO ≤ 6%, 2.0% ≤ P2O5 ≤ 5.0%, moisture ≤ 12.0%, R2O ≤ 1.50%; Phosphogypsum I: crystal water ≥ 16.00%, CaCO3 ≤ 0, MgCO3 ≤ 0, moisture ≤ 12.0%, Loss ≤ 18.00%, SO3 ≥ 38.00%, P2O5 ≤ 0.80%; Copper slag: Fe2O3 ≥ 50.0%, R2O ≤ 1.50%, moisture ≤ 10.0%.

3. The commercial concrete cement according to claim 1 or 2, characterized in that: In the cement grinding, by mass percentage, clinker is 75.92% ± 1.0%, phosphogypsum II is 6.0% ± 0.5%, fly ash is 1.5% ± 0.5%, granulated blast furnace slag is 12.0% ± 0.5%, limestone II is 4.5 ± 0.5%, and special grinding aid is 0.08% ± 0.02%.

4. The commercial concrete cement according to claim 3, characterized in that: By mass percentage, the raw material indexes meet at least one of the following: Phosphogypsum II: Crystal water ≥ 16.00%, Total moisture ≤ 12.0%, Loss ≤ 18.00%, SO3 ≥ 38.00%, P2O5 ≤ 0.80%, Chloride ion ≤ 0.5%, pH value ≥ 8.0, Radionuclide limit I Ra , I r ≤ 0.9; Fly ash: Loss ≤ 6.0%, water content ≤ 0.8%, SO3 ≤ 3.0%, f-CaO ≤ 2.0%, combined content of SiO2 + Al2O3 + Fe2O3 ≥ 70.0%, density ≤ 2.5 g / cm 3 , soundness qualified, CaSO3﹒1 / 2H2O ≤ 2.5%, ammonium ion content ≤ 180 mg / kg, radionuclide limit I Ra 、I r ≤ 0.9, R2O ≤ 2.0%; Granulated blast furnace slag: mass coefficient ≥ 1.3, TiO2 ≤ 9.6%, MnO ≤ 9.6%, F ≤ 1.8%, sulfide ≤ 2.5%, bulk density ≤ 1.1×10 3 Kg / m 2 , maximum particle size ≤ 40 mm, particles larger than 10 mm ≤ 6.0%, vitreous content ≥ 75%, radionuclide limit I Ra 、I r ≤ 0.8, water-soluble chromium (VI) ≤ 8.0 mg / kg; Limestone II: CaO ≥ 50.00%, MgO ≤ 3.00%, residue on 50 mm sieve ≤ 15.0%, methylene blue value ≤ 1.1 g / kg, radionuclide limit I Ra and I r ≤ 0.8, water-soluble chromium (VI) ≤ 8.0 mg / kg; Special grinding aid: Grace ES5869, containing components with retarding and slump retention effects. The difference in solid content between two adjacent batches of the same model of grinding aid does not exceed 2.0, the difference in density does not exceed 0.03, and the difference in pH does not exceed 1.

0.

5. The commercial concrete cement according to any one of claims 1 to 4, characterized in that: The coal consumption is 7.0 - 9.0% of the raw material amount, and the usage ratio of head coal to tail coal is 3:

7.

6. The commercial concrete cement according to any one of claims 1 to 5, characterized in that: The quality indexes of the ground commercial concrete cement include: specific surface area 370±10m 2 / Kg, residue fineness on 45um sieve 8.0%±1%; and / or The factory quality indexes of the commercial concrete cement include: initial setting 200 - 230 min, final setting 260 - 290 min, 1-hour time-dependent loss ≥ -80 mm and ≤ 10 mm, 28-day compressive strength 53.0 MPa ± 2.0 MPa.

7. The preparation method of the commercial concrete cement according to any one of claims 1 to 6, characterized in that: It includes the following steps: S1. Grind and homogenize the raw materials limestone I, sandstone, aluminum ore waste rock, coal gangue, copper slag, phosphorus slag, phosphogypsum I and copper slag; S2. Pre-decompose and calcine the homogenized raw materials into clinker; S3. After the clinker is cooled and homogenized, co-grind it with phosphogypsum II, fly ash, granulated blast furnace slag, limestone II and special grinding aid into cement.

8. According to the preparation method described in claim 7, it is characterized in that: In step S1, control the lime saturation factor KH of the homogenized raw meal: 0.950 ± 0.020, the silica modulus SM: 2.35 ± 0.10, and the alumina modulus IM: 1.50 ± 0.10; and / or In step S2, control the lime saturation factor KH of the calcined clinker: 0.910 ± 0.020, the silica modulus SM: 2.35 ± 0.10, and the alumina modulus IM: 1.50 ± 0.

10.

9. The preparation method according to claim 7 or 8, characterized in that: In step S2, the calcination temperature is 1420 ± 30 °C, the oxygen content > 1.5%, and the internal and external air pressures > 55 kPa; in step S3, the clinker cooling temperature is 65 °C lower than room temperature.

10. The preparation method according to any one of claims 7 to 9, characterized in that: In step S3, the grinding fineness is controlled such that the specific surface area is 370 ± 10 m 2 / kg, the residue fineness on a 45-μm sieve is 8.0% ± 1%, and the comprehensive moisture content entering the mill is < 1%.

Images