CN111747665A - Manufacturing process of finished cement added with Bayer process red mud - Google Patents

Manufacturing process of finished cement added with Bayer process red mud Download PDF

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CN111747665A
CN111747665A CN202010450627.2A CN202010450627A CN111747665A CN 111747665 A CN111747665 A CN 111747665A CN 202010450627 A CN202010450627 A CN 202010450627A CN 111747665 A CN111747665 A CN 111747665A
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red mud
bayer
bittern
weight ratio
content
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CN111747665B (en
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高一飞
牛安逸
凌德
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Intercontinental Institute Of Environmental Sciences Guangzhou Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/02—Portland cement
    • C04B7/04—Portland cement using raw materials containing gypsum, i.e. processes of the Mueller-Kuehne type
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/02—Portland cement
    • C04B7/06—Portland cement using alkaline raw materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C04B7/26—Cements from oil shales, residues or waste other than slag from raw materials containing flue dust, i.e. fly ash
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Sludge (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The invention discloses a manufacturing process of finished cement added with Bayer process red mud. The method compares the oxide percentages of various Bayer red mud, and determines a set of effective batching schemes (CaO accounts for 2.5-10% and SiO accounts for 2.5-10%) after large-scale experimental exploration211-20% of Na2O 1％～2.5％、SiO2/Al2O3The proportion of (A) is 0.55-0.85), the activity of the Bayer red mud can be effectively maintained, the addition amount of the Bayer red mud in cement is increased, and the reutilization of solid wastes is realized.

Description

Manufacturing process of finished cement added with Bayer process red mud
Technical Field
The invention belongs to the field of cement manufacturing, and particularly relates to a manufacturing process of finished cement added with Bayer process red mud.
Background art:
the red mud is an industrial waste residue generated in the production of alumina. Statistically, about 1.5t of red mud is discharged for every 1t of alumina produced. The total stockpiling quantity of red mud worldwide has exceeded 40 hundred million tons in 2015, and is increasing in an amount of 1.5 hundred million tons per year. The total stock of red mud in china has reached 6 million tons and is still growing in an amount of 8800 million tons per year. The piling up of the red mud occupies a large amount of land area, and the red mud has strong alkalinity, and part of the red mud also has radioactivity, so the piling up seriously affects the ecological balance and causes great harm to the human health.
Bayer process red mud is red mud generated when alumina is extracted by adopting a Bayer process, 95% of alumina in the world is extracted by the Bayer process, the generated Bayer process red mud has the characteristics of high iron and aluminum content, low calcium oxide content and the like, and researches show that the CaO content in the Bayer process red mud is only 0.5%, but the iron and aluminum content is as high as 64.5%. The most promising application field of the red mud is the application in the building field, so that the failure to prepare cement by using the red mud of the Bayer process greatly limits the consumption of the red mud of the Bayer process.
Currently, a method for preparing ordinary portland cement by replacing ordinary portland cement clinker with red mud has been developed partially, and patent CN 110194630 a discloses a method for preparing cement concrete by replacing ordinary portland cement with two solid wastes of red mud-yellow phosphorus slag; however, the mixing proportion of the red mud is only 10%, and the utilization efficiency of the solid waste of the red mud is low.
The invention content is as follows:
in order to overcome the defects, the invention provides a process for preparing finished cement by adding Bayer process red mud, which can improve the doping component of the red mud to 16-30%, greatly improve the utilization efficiency of the Bayer process red mud, and simultaneously prepare cement concrete with excellent performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
A. dealkalizing Bayer red mud to reduce the alkalinity of the red mud and reduce Na in the red mud2O content, if CaO, SiO in the dealkalized Bayer red mud2、Na2The weight proportion of O is 2.5 to 10 percent11 to 20 percent of the total weight of the red mud, and 1 to 2.5 percent of the total weight of the red mud, so that the SiO in the Bayer red mud is reduced2/Al2O3The weight ratio of the raw materials is 0.55-0.85, and then calcining is carried out, so as to obtain a calcined material;
if the oxide of the dealkalized Bayer red mud can not meet the proportion, limestone or fly ash is doped for oxide adjustment, so that CaO and SiO in the dealkalized Bayer red mud2、Na2The weight ratio of O is 2.5-10%, 11-20% and 1-2.5%, so that SiO in the Bayer red mud is obtained2/Al2O3The weight ratio of (A) to (B) is 0.55-0.85; if limestone is doped into the dealkalized Bayer red mud, the limestone needs to be uniformly mixed with the dealkalized Bayer red mud before calcination, and then calcination is carried out; if fly ash is doped into dealkalized Bayer red mud, calcining the Bayer red mud, and uniformly mixing the calcined Bayer red mud with the fly ash after the calcined Bayer red mud is placed at normal temperature; thereby obtaining a calcined material;
drying the material until the water content is lower than 1%, and sieving to obtain a sieved material;
B. the raw materials are calculated according to the mass fraction of 100 percent: 20-30% of sieved materials, 65-75% of finished cement clinker of a cement plant and the balance of desulfurized gypsum of the power plant are uniformly mixed and ground to obtain the common Portland cement.
Generally powder to a specific surface area of 300m2The cement is prepared into ordinary portland cement in kg and meets the standard of general portland cement (GB 175-2007).
Preferably, the calcination is carried out to 900-1000 ℃ for 1-2 h;
preferably, in step a, the sieving is a 180 mesh sieve.
Preferably, the dealkalization treatment of the Bayer red mud is to mix and stir flue gas desulfurization slag and bittern with a Bayer red mud aqueous solution, and then squeeze the slurry to dry to obtain the dealkalized Bayer red mud.
Preferably, the dealkalization treatment of the bayer red mud comprises the following specific steps:
raw materials: red mud, flue gas desulfurization slag and bittern;
a. measuring the content of gypsum in the flue gas desulfurization slag, measuring the content of magnesium ions in bittern, and converting into magnesium chloride;
b. and (3) measuring the alkalinity of the red mud water extract:
adding 10 g of dried red mud into 50 ml of deionized water, oscillating on an oscillator for 1 hour, taking 25ml of extracting solution, continuously titrating the 25ml of extracting solution by using 0.05M HCl solution until the pH value is 7, and obtaining the alkalinity of the water extracting solution of the red mud by using the following formula according to the volume of the consumed HCl solution:
alkalinity (millimole/kg) of the red mud water extract is 2v × 0.05 × 100 v ═ 10 v; wherein v is the number of milliliters of HCl solution consumed by titrating the red mud water extract;
c. method for measuring total alkalinity of red mud
Taking 10 g of dried red mud, adding 20 ml of 0.05M hydrochloric acid solution to obtain red mud suspension, continuously titrating the red mud suspension by using 0.05M HCl solution until the pH value of the final point is 7, and calculating the total alkalinity of the red mud by using the following formula according to the volume of the consumed HCl solution:
total basicity (millimole/kg) — (v +20) × 0.05 × 100 ═ v +20) x 5 of red mud
In the above formula, v is the number of milliliters of HCl solution consumed by titrating the red mud suspension;
d. removal of OH in red mud by calcium sulfate-The capacity (millimole/kg) of 1000/86 × 1000-11627;
according to the designed dose-response experiment, continuously monitoring the pH of the reaction solution, wherein the detection time is 10, 25 and 50 hours after the test is started, if the pH is not close to 9 after 50 hours, measuring the pH once again every 25 hours until the pH is close to 9, and determining the addition amount of the pure gypsum required for reducing the pH of the red mud to be less than 9, namely the actual weight ratio of the calcium sulfate to the red mud;
e. removal of OH in red mud by magnesium chloride-Capacity (millimole/kg) of 1000/101.5 × 1000-9852
Magnesium chloride/red mud ratio (alkalinity of red mud water extract/9852)
f. Carrying out comprehensive analysis and determining the weight ratio of magnesium chloride to calcium sulfate during red mud treatment to be
The actual calcium sulphate/red mud weight ratio: the ratio of magnesium chloride to red mud is equal to the weight ratio of magnesium chloride to calcium sulfate;
then determining the dosage of bittern and flue gas desulfurization slag when treating the red mud according to the content of gypsum in the flue gas desulfurization slag and the content of magnesium chloride in the bittern;
g. the method for measuring the water content of the red mud is characterized in that the dosage of bittern and flue gas desulfurization slag obtained by calculating the dried red mud is converted into the dosage of fresh red mud;
h. inputting the red mud into a reaction tank, and mixing the raw materials according to the weight ratio of the red mud: adding water according to the weight ratio of 1:2.5, adding bittern and flue gas desulfurization slag with the amount not less than the amount determined in the step g, stirring, inputting slurry into a filter press, and conveying the squeezed red mud to a storage yard. The squeezed water is recycled.
Preferably, the determination of the content of the gypsum in the flue gas desulfurization slag is directly performed by using an X-ray fluorescence spectrometer (XRF) and an X-ray diffractometer (XRD).
Preferably, the determination of the content of magnesium ions in the bittern is performed by using an inductively coupled plasma optical emission spectroscopy (ICP-OES) instrument or an atomic absorption spectrometer (ASS).
The invention has the advantages of
The process of the patent application relates to the application of Bayer process red mud, because CaO and SiO in the Bayer process red mud2、Al2O3The content of the red mud is related to the refining process of alumina and the taste of bauxite used, and the Na2O is related to the dealkalization process of the red mud, so the red mud produced by different manufacturers, different raw materials and different treatment processes has different components. The existing research shows that when the red mud is used as a cement admixture to prepare ordinary portland cement, the types of formed hydration products and SiO in the red mud2、Al2O3、CaO、Na2The percentage of O is related to the oxide or base content (Na) of the composition2O+0.658K2O) may cause a change in the type of hydration product of the final cement, resulting in unstable cement quality. The oxide percentages of various Bayer red mud are compared, and large-scale experiment exploration is performedThen, a set of effective batching scheme (CaO accounts for 2.5% -10%, SiO) is determined211-20% of Na2O 1％～2.5％、SiO2/Al2O3The proportion of (A) is 0.55-0.85), the activity of the Bayer red mud can be effectively maintained, the addition amount of the Bayer red mud in cement is increased, and the reutilization of solid wastes is realized.
Description of the drawings:
fig. 1 is a dose-response curve of bayer red mud;
fig. 2 is a schematic view of a bayer red mud treatment plant.
The specific implementation mode is as follows:
the following examples are further illustrative of the present invention and are not intended to be limiting thereof.
The method comprises the following specific steps of dealkalizing the Bayer red mud:
raw materials: red mud, flue gas desulfurization slag and bittern;
a. measuring the content of gypsum in the flue gas desulfurization slag, measuring the content of magnesium ions in bittern, and converting into magnesium chloride;
b. and (3) measuring the alkalinity of the red mud water extract:
adding 10 g of dried red mud into 50 ml of deionized water, oscillating on an oscillator for 1 hour, taking 25ml of extracting solution, continuously titrating the 25ml of extracting solution by using 0.05M HCl solution until the pH value is 7, and obtaining the alkalinity of the water extracting solution of the red mud by using the following formula according to the volume of the consumed HCl solution:
alkalinity (millimole/kg) of the red mud water extract is 2v × 0.05 × 100 v ═ 10 v; wherein v is the number of milliliters of HCl solution consumed by titrating the red mud water extract;
c. method for measuring total alkalinity of red mud
Taking 10 g of dried red mud, adding 20 ml of 0.05M hydrochloric acid solution to obtain red mud suspension, continuously titrating the red mud suspension by using 0.05M HCl solution until the pH value of the final point is 7, and calculating the total alkalinity of the red mud by using the following formula according to the volume of the consumed HCl solution:
total basicity (millimole/kg) — (v +20) × 0.05 × 100 ═ v +20) x 5 of red mud
In the above formula, v is the number of milliliters of HCl solution consumed by titrating the red mud suspension;
d. removal of OH in red mud by calcium sulfate-The capacity (millimole/kg) of 1000/86 × 1000-11627;
according to the designed dose-response experiment, continuously monitoring the pH of the reaction solution, wherein the detection time is 10, 25 and 50 hours after the test is started, if the pH is not close to 9 after 50 hours, measuring the pH once again every 25 hours until the pH is close to 9, and determining the addition amount of the pure gypsum required for reducing the pH of the red mud to be less than 9, namely the actual weight ratio of the calcium sulfate to the red mud;
e. removal of OH in red mud by magnesium chloride-Capacity (millimole/kg) of 1000/101.5 × 1000-9852
Magnesium chloride/red mud ratio (alkalinity of red mud water extract/9852)
f. Carrying out comprehensive analysis and determining the weight ratio of magnesium chloride to calcium sulfate during red mud treatment to be
The actual calcium sulphate/red mud weight ratio: the ratio of magnesium chloride to red mud is equal to the weight ratio of magnesium chloride to calcium sulfate;
then determining the dosage of bittern and flue gas desulfurization slag when treating the red mud according to the content of gypsum in the flue gas desulfurization slag and the content of magnesium chloride in the bittern;
g. the method for measuring the water content of the red mud is characterized in that the dosage of bittern and flue gas desulfurization slag obtained by calculating the dried red mud is converted into the dosage of fresh red mud;
h. inputting the red mud into a reaction tank, and mixing the raw materials according to the weight ratio of the red mud: adding water according to the weight ratio of 1:2.5, adding bittern and flue gas desulfurization slag with the amount not less than the amount determined in the step g, stirring, inputting slurry into a filter press, and conveying the squeezed red mud to a storage yard. The squeezed water is recycled.
The content of the gypsum in the flue gas desulfurization slag is directly measured by using an X-ray fluorescence spectrometer (XRF) and an X-ray diffractometer (XRD).
The measurement of the content of the magnesium ions in the bittern is carried out by using an inductively coupled plasma optical emission spectroscopy (ICP-OES) instrument or an atomic absorption spectrometer (ASS).
Example 1:
firstly, preparing dealkalized Bayer red mud:
the pH value of the Bayer red mud is 11.27;
1. the method for measuring the alkalinity of each red mud water extract comprises the following steps: approximately 10 g of dried red mud (exactly 0.01 g) was placed in a 100 ml plastic bottle with a lid, 50 ml of deionized water was added, shaken on a shaker for 1 hour, 25ml of extract was taken, and 25ml of extract was titrated continuously with 0.05M standardized HCl solution on an autotitrator to the end point (pH 7). According to the volume of the consumed HCl solution, the alkalinity of the water extract of the red mud is obtained by the following formula:
alkalinity (millimole/kg) of extract of red mud water 2v x 0.05x 100 10v
In the above formula, v is the number of milliliters of HCl solution consumed for titrating the extract of red mud water.
2. The method for measuring the total alkalinity of the red mud comprises the following steps: about 10 g of dried red mud (accurate to 0.01 g) was taken, 20 ml of 0.05M solution of standardized hydrochloric acid (HCl) was added, and the red mud suspension was titrated continuously to the end point (pH 7) with 0.05M solution of standardized HCl on an autotitrator. According to the volume of the consumed HCl solution, the total alkalinity of the red mud is obtained by the following formula:
total alkalinity (millimole/kg) of red mud, (v +20) x 0.05x 100, (v +20) x 5
In the above formula, v is the ml of HCl solution consumed for titrating the red mud suspension.
3. The slow release alkalinity of the red mud is the difference between the total alkalinity of the red mud and the alkalinity of the red mud water extract, and is calculated by the following formula:
the red mud slowly releases alkalinity (millimole/kg) ═ total alkalinity of red mud-alkalinity of red mud water extract
The alkalinity of the red mud water extract and the total alkalinity of the red mud were obtained from the above three samples, and the results are shown in Table 1
TABLE 1
Consumption of 0.05M HCl volume (ml) Alkalinity (millimole/kg)
Alkalinity of Bayer red mud water extract 11.5 115
Total alkalinity of Bayer red mud 128.3 741.5
Determining the proportion of the treating agent to the red mud
1. According to the measured total alkalinity of the red mud, determining to remove OH in the red mud-The desired theoretical calcium sulfate/red mud weight ratio. The dose-response experiment was designed accordingly and the pH of the reaction solution was monitored continuously for the 10 th, 25 th and 50 th hours after the start of the experiment. If the pH is not close to 9 after 50 hours, the measurement is performed again every 25 hours until the pH is close to 9. Determining the pure gypsum required for reducing the pH of the red mud to below 9, namely calcium sulfate dihydrate (CaSO)4·2H2O) is added. The method comprises the following specific steps:
removing OH from red mud by calcium sulfate (i.e. calcium sulfate dihydrate, the same applies below)-Capacity (mmol/kg) of 1000/86 × 1000 11627
Therefore, the temperature of the molten metal is controlled,
setting the weight ratio of calcium sulfate/red mud of Bayer red mud to be 741.5 (millimole/kg)/11627 (millimole/kg) to be 0.064, and accordingly setting the calcium sulfate additive amount interval of the Bayer red mud to be 0 to 0.1;
in actual operation, a group (6 parts) of dried red mud (accurate to 0.01 g) with the weight of 50 g is weighed for each sample and put into a plastic bottle with the volume of 150 ml, and different amounts of pure calcium sulfate are respectively added. The bayer red mud has calcium sulfate/red mud weight ratios set at 0, 0.03, 0.05, 0.07, 0.09, and 1.00. After adding calcium sulfate, respectively adding 100 ml of pure water into each bottle, tightly covering the bottle cap, oscillating on an oscillator for 10 hours, and then measuring the pH value of the solution; then continuing oscillating the sample for 15 hours, and then measuring the pH value of the solution again; the sample was then shaken for an additional 25 hours before the pH of the solution was again measured. At this point the pH was still not close to 9, so the shaking and pH measurements were continued every 25 hours. The pH of the sample dropped below 9 (fig. 1) after 50 hours of shaking. From the dose-response curve it was determined that to reduce the pH of the red mud sample 2 below 9, the calcium sulfate/red mud ratio needed to reach 0.07.
2. Determining to rapidly eliminate free OH in red mud according to alkalinity of water extract of sample-Magnesium chloride hexahydrate (MgCl)2·6H2O) to determine the magnesium chloride/red mud weight ratio.
The method comprises the following specific steps:
removing OH in red mud by magnesium chloride (namely magnesium chloride hexahydrate)-Capacity (millimole/kg) of 1000/101.5 × 1000-9852
Therefore, the temperature of the molten metal is controlled,
the magnesium chloride/red mud ratio of the sample was 115 (mmol/kg)/9852 (mmol/kg) 0.012
3. Carrying out comprehensive analysis and determining the weight ratio of magnesium chloride to calcium sulfate when treating the red mud as follows:
samples of magnesium chloride/calcium sulfate 0.012/0.07-0.17 (i.e., 1.7:10)
On-site treatment of fresh red mud in factory
1. During on-site construction, according to the theoretical calcium sulfate/red mud ratio and the magnesium chloride/red mud ratio obtained above, the on-site pilot test is carried out on the red mud to be treated by combining the results of measuring the content of gypsum in the flue gas desulfurization slag, the content of magnesium ions in bittern and the water content of the red mud. On the basis, in consideration of the complexity of field construction, such as the space-time variability of alkalinity in the red mud to be treated, the uncertainty of the mixing degree of the treating agent and the red mud, the limitation of reaction time and the like, the proportion of the treating agent and the red mud needs to be increased so as to ensure that the preset treatment target is achieved. The following describes how to apply the method by taking the bayer red mud at the location of the sample as an example:
the content of gypsum in the flue gas desulfurization slag is directly measured by using an X-ray fluorescence spectrometer (XRF) and an X-ray diffractometer (XRD). The flue gas desulfurization residue used was estimated to contain about 77% gypsum.
The purity of magnesium chloride in bittern was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) instrument or atomic absorption spectroscopy (ASS). The bittern used was measured to contain 66.8 g/l magnesium ions, converted to 566 g/l magnesium chloride hexahydrate.
Determining the water content of the Bayer red mud: taking about 10 g of fresh Bayer red mud (accurate to 0.01 g) in a 50 ml glass beaker, drying in an oven controlled at 105 ℃ to constant weight, wherein the water content of the Bayer red mud is calculated by the following formula:
bayer red mud water content (%) - (fresh red mud weight-dried red mud weight)/fresh red mud weight x 100
The water content of the Bayer red mud to be treated is measured to be 36 percent.
2. 50 g of fresh Bayer red mud (equivalent to 32 g of dried red mud) is placed in a 150 ml beaker, and 3g of flue gas desulfurization residue (32 g x 0.07/0.77), 1 ml of bittern (about 0.57 g of magnesium chloride) and 125 ml of water are added
After mixing, the suspension was stirred for 30 minutes on a magnetic stirrer and the pH of the suspension was determined to be 8.87.
3. The on-site treatment of about 40 tons of bayer red mud comprises the following steps: mixing Bayer red mud and water of about 125 cubic meters to form slurry, conveying the slurry into a first-stage reaction tank, adding bittern of 1.25 cubic meters, stirring for half an hour, adding 3 tons of flue gas desulfurization slag, and continuously stirring in the stirring tank for half an hour to obtain a suspension with the pH value of 7.75. Then the treated mud is input into a filter press, the dried Bayer red mud (dealkalized Bayer red mud) is conveyed to a yard, and the squeezed water is recycled (see figure 2). The dealkalized bayer red mud of the other examples was the dealkalized bayer red mud prepared in this example.
Secondly, 30g dealkalized Bayer red mud (CaO accounts for 2.7 percent, SiO)212.7% by weight, Al2O3Is 23.3 percent，Na2The O content is 2.5 percent, the silicon-aluminum ratio (SiO2/Al2O3) is 0.55), the mixture is calcined in a muffle furnace to 900 ℃, kept for 1 hour and taken out after calcination. The red mud is fully and uniformly mixed with 112.5g of cement clinker and 7.5g of gypsum, and the mixture is ground into powder with the specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 29.6MPa and 48.7MPa, and the flexural strength of 3 days and 28 days is 5.9MPa and 8.8 MPa. The percentage contents of the red mud, the cement clinker and the gypsum in the prepared ordinary portland cement are respectively 20%, 75% and 5%.
Example 2
45g dealkalized Bayer red mud (CaO accounting for 2.7 percent, SiO2 accounting for 12.7 percent, Al2O3 accounting for 23.3 percent, Na2O accounting for 2.5 percent and Si/Al accounting for 0.55 percent) is calcined in a muffle furnace to 900 ℃, kept for 2 hours and taken out after calcination. The red mud is fully and uniformly mixed with 97.5g of cement clinker and 7.5g of gypsum, and the mixture is ground to the specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 27.5MPa and 38.7MPa, and the flexural strength of 3 days and 28 days is 4.5MPa and 5.6 MPa. The percentage contents of the red mud, the cement clinker and the gypsum in the prepared ordinary portland cement are respectively 30%, 65% and 5%.
Example 3
After 27g dealkalized Bayer red mud and 3g limestone are mixed uniformly, the mixture is sieved by a 180-mesh sieve (CaO accounts for 8.1 percent, SiO2 accounts for 11.43 percent, Al2O3 accounts for 21 percent, Na2O accounts for 2.25 percent and Si/Al ratio is 0.55) and calcined in a muffle furnace to 1000 ℃, kept for 1 hour and taken out after calcination. Fully and uniformly mixing the burned cement mixture with 112.5g of cement clinker and 7.5g of gypsum, and grinding the mixture to a specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 29.2MPa and 48MPa, and the flexural strength of 3 days and 28 days is 5.8MPa and 8 MPa. The percentage contents of the red mud, the limestone, the cement clinker and the gypsum in the manufactured ordinary portland cement are respectively 18%, 2%, 75% and 5%.
Example 4
Mixing 25.8g dealkalized Bayer red mud and 4.2g limestone uniformly, and sieving with 180 mesh sieveThe sieve (CaO content 10.2%, SiO2 content 10.9%, Al2O3 content 20.0%, Na2O content 2.15%, Si/Al content 0.55) was calcined in a muffle furnace to 1000 deg.C, held for 1h, and taken out after calcination. Fully and uniformly mixing the burned cement mixture with 112.5g of cement clinker and 7.5g of gypsum, and grinding the mixture to a specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 28.8MPa and 46.6MPa, and the flexural strength of 3 days and 28 days is 5.7MPa and 7.9 MPa. The percentage contents of red mud, limestone, cement clinker and gypsum in the prepared ordinary portland cement are respectively 17.2%, 2.8%, 75% and 5%.
Example 5
27g dealkalized Bayer red mud is sieved by a 180-mesh sieve, burned to 900 ℃, kept for 1h, taken out after being calcined, and stirred and mixed with 3g fly ash uniformly to prepare a cement admixture (the CaO accounts for 3.7%, the SiO2 accounts for 16.3%, the Al2O3 accounts for 23.8%, the Na2O accounts for 2.25%, and the silicon-aluminum ratio is 0.68). Mixing the cement mixture with 112.5g of cement clinker and 7.5g of gypsum, and grinding to obtain a powder with a specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 29.9MPa and 48.3MPa, and the flexural strength of 3 days and 28 days is 6.2MPa and 8.8 MPa. The percentage contents of the red mud, the fly ash, the cement clinker and the gypsum in the prepared ordinary portland cement are respectively 18.0%, 2.0%, 75% and 5%.
Example 6
25.5g dealkalized Bayer red mud is sieved by a 180-mesh sieve, burned to 900 ℃, kept for 1h, taken out after being calcined, and stirred and mixed with 4.5g fly ash uniformly to prepare cement admixture (CaO accounts for 4.2%, SiO2 accounts for 18.1%, Al2O3 accounts for 24.1%, Na2O accounts for 2.1%, and silicon-aluminum accounts for 0.75%). Mixing the cement mixture with 112.5g of cement clinker and 7.5g of gypsum, and grinding to obtain a powder with a specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 30.3MPa and 50.3MPa, and the flexural strength of 3 days and 28 days is 6.2MPa and 9 MPa. The prepared ordinary portland cement contains the red mud, the fly ash, the cement clinker and the gypsum in percentageThe amounts were 17.0%, 3.0%, 75% and 5%, respectively.
Example 7
24g dealkalized Bayer red mud is sieved by a 180-mesh sieve, burned to 900 ℃, kept for 1h, taken out after being calcined, and stirred and mixed with 6g fly ash uniformly to prepare a cement admixture (CaO accounts for 4.7%, SiO2 accounts for 19.9%, Al2O3 accounts for 24.3%, Na2O accounts for 2%, and Si/Al ratio is 0.82). Mixing the cement mixture with 112.5g of cement clinker and 7.5g of gypsum, and grinding to obtain a powder with a specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 31.6MPa and 50.5MPa, and the flexural strength of 3 days and 28 days is 6.4MPa and 9 MPa. The percentage contents of red mud, fly ash, cement clinker and gypsum in the prepared ordinary portland cement are respectively 16.0%, 4.0%, 75% and 5%.
Example 8
Calcining 30g dealkalized Bayer red mud (CaO accounting for 2.8%, SiO2 accounting for 12.9%, Al2O3 accounting for 23.6%, Na2O accounting for 1.2%, and Si/Al accounting for 0.55%) in a muffle furnace to 900 ℃, keeping the temperature for 1h, and taking out after calcination. The red mud is fully and uniformly mixed with 112.5g of cement clinker and 7.5g of gypsum, and the mixture is ground into powder with the specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 29.3MPa and 47.2MPa, and the flexural strength of 3 days and 28 days is 5.7MPa and 8.5 MPa. The percentage contents of the red mud, the cement clinker and the gypsum in the prepared ordinary portland cement are respectively 20%, 75% and 5%.
Example 9
Calcining 45g dealkalized Bayer red mud (CaO accounting for 2.8%, SiO2 accounting for 12.9%, Al2O3 accounting for 23.6%, Na2O accounting for 1.2%, and Si/Al accounting for 0.55%) in a muffle furnace to 900 ℃, keeping the temperature for 2h, and taking out after calcination. The red mud is fully and uniformly mixed with 97.5g of cement clinker and 7.5g of gypsum, and the mixture is ground to the specific surface area of 300m2And/kg, and preparing the ordinary portland cement. According to the cement standard mortar strength test GB/T17671-1999, the compressive strength of 3 days and 28 days is 26.5MPa and 37.6MPa, and the flexural strength of 3 days and 28 days is 3.9MPa and 5.5 MPa. Red mud, cement clinker and gypsum in the produced ordinary portland cementThe percentage contents of (A) are respectively 30%, 65% and 5%.

Claims (7)

1. A manufacturing process of finished cement added with Bayer process red mud is characterized by comprising the following steps:
A. dealkalizing Bayer red mud, if CaO and SiO in the dealkalized Bayer red mud2、Na2The weight ratio of O is 2.5-10%, 11-20% and 1-2.5%, so that SiO in the Bayer red mud is obtained2/Al2O3The weight ratio of the raw materials is 0.55-0.85, and then calcining is carried out, so as to obtain a calcined material;
if the oxide of the dealkalized Bayer red mud can not meet the proportion, limestone or fly ash is doped for oxide adjustment, so that CaO and SiO in the dealkalized Bayer red mud2、Na2The weight ratio of O is 2.5-10%, 11-20% and 1-2.5%, so that SiO in the Bayer red mud is obtained2/Al2O3The weight ratio of (A) to (B) is 0.55-0.85; if limestone is doped into the dealkalized Bayer red mud, the limestone needs to be uniformly mixed with the dealkalized Bayer red mud before calcination, and then calcination is carried out; if fly ash is doped into dealkalized Bayer red mud, calcining the Bayer red mud, and uniformly mixing the calcined Bayer red mud with the fly ash after the calcined Bayer red mud is placed at normal temperature; thereby obtaining a calcined material;
drying the material until the water content is lower than 1%, and sieving to obtain a sieved material;
B. the raw materials are calculated according to the mass fraction of 100 percent: 20-30% of sieved materials, 65-75% of finished cement clinker of a cement plant and the balance of desulfurized gypsum of the power plant are uniformly mixed and ground to obtain the common Portland cement.
2. The manufacturing process of the finished cement added with the Bayer process red mud as claimed in claim 1, wherein the calcination is carried out to 900-1000 ℃ for 1-2 h.
3. The process for manufacturing a finished cement added with bayer red mud according to claim 1, wherein in the step a, the screening is 180-mesh.
4. The process for manufacturing the finished cement added with the Bayer process red mud according to claim 1, wherein the dealkalization treatment on the Bayer red mud is to mix and stir flue gas desulfurization slag and bittern with a Bayer red mud aqueous solution, and then squeeze the mud to dry to obtain the dealkalized Bayer red mud.
5. The process for manufacturing the finished cement added with the Bayer process red mud according to claim 4, wherein the dealkalization treatment of the Bayer red mud comprises the following specific steps:
raw materials: red mud, flue gas desulfurization slag and bittern;
a. measuring the content of gypsum in the flue gas desulfurization slag, measuring the content of magnesium ions in bittern, and converting into magnesium chloride;
b. and (3) measuring the alkalinity of the red mud water extract:
adding 10 g of dried red mud into 50 ml of deionized water, oscillating on an oscillator for 1 hour, taking 25ml of extracting solution, continuously titrating the 25ml of extracting solution by using 0.05M HCl solution until the pH value is 7, and obtaining the alkalinity of the water extracting solution of the red mud by using the following formula according to the volume of the consumed HCl solution:
alkalinity (millimole/kg) of the red mud water extract is 2v × 0.05 × 100 v ═ 10 v; wherein v is the number of milliliters of HCl solution consumed by titrating the red mud water extract;
c. method for measuring total alkalinity of red mud
Taking 10 g of dried red mud, adding 20 ml of 0.05M hydrochloric acid solution to obtain red mud suspension, continuously titrating the red mud suspension by using 0.05M HCl solution until the pH value of the final point is 7, and calculating the total alkalinity of the red mud by using the following formula according to the volume of the consumed HCl solution:
total basicity (millimole/kg) — (v +20) × 0.05 × 100 ═ v +20) x 5 of red mud
In the above formula, v is the number of milliliters of HCl solution consumed by titrating the red mud suspension;
d. removal of OH in red mud by calcium sulfate-The capacity (millimole/kg) of 1000/86 × 1000-11627;
according to the designed dose-response experiment, continuously monitoring the pH of the reaction solution, wherein the detection time is 10, 25 and 50 hours after the test is started, if the pH is not close to 9 after 50 hours, measuring the pH once again every 25 hours until the pH is close to 9, and determining the addition amount of the pure gypsum required for reducing the pH of the red mud to be less than 9, namely the actual weight ratio of the calcium sulfate to the red mud;
e. removal of OH in red mud by magnesium chloride-Capacity (millimole/kg) of 1000/101.5 × 1000-9852
Magnesium chloride/red mud ratio (alkalinity of red mud water extract/9852)
f. Carrying out comprehensive analysis and determining the weight ratio of magnesium chloride to calcium sulfate during red mud treatment to be
The actual calcium sulphate/red mud weight ratio: the ratio of magnesium chloride to red mud is equal to the weight ratio of magnesium chloride to calcium sulfate;
then determining the dosage of bittern and flue gas desulfurization slag when treating the red mud according to the content of gypsum in the flue gas desulfurization slag and the content of magnesium chloride in the bittern;
g. the method for measuring the water content of the red mud is characterized in that the dosage of bittern and flue gas desulfurization slag obtained by calculating the dried red mud is converted into the dosage of fresh red mud;
h. inputting the red mud into a reaction tank, and mixing the raw materials according to the weight ratio of the red mud: adding water according to the weight ratio of 1:2.5, adding bittern and flue gas desulfurization slag with the amount not less than the amount determined in the step g, stirring, inputting slurry into a filter press, and conveying the squeezed red mud to a storage yard.
6. The process for manufacturing the finished cement added with the Bayer process red mud as claimed in claim 5, wherein the step of measuring the content of the gypsum in the flue gas desulfurization slag is directly carried out by using an X-ray fluorescence spectrometer and an X-ray diffractometer.
7. The process for manufacturing the finished cement added with the Bayer process red mud as claimed in claim 5, wherein the step of measuring the content of the magnesium ions in the bittern is to measure the magnesium ions in the bittern by using an inductively coupled plasma optical emission spectrometer or an atomic absorption spectrometer.
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