CN115093135B - Process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization - Google Patents

Process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization Download PDF

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CN115093135B
CN115093135B CN202210825823.2A CN202210825823A CN115093135B CN 115093135 B CN115093135 B CN 115093135B CN 202210825823 A CN202210825823 A CN 202210825823A CN 115093135 B CN115093135 B CN 115093135B
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phosphogypsum
desulfurization
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cement clinker
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CN115093135A (en
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李叶青
张克昌
余松柏
孙航
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Huaxin Cement 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
    • C04B7/32—Aluminous cements
    • C04B7/323—Calcium aluminosulfate cements, e.g. cements hydrating into ettringite
    • 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
    • C04B7/24—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
    • 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
    • C04B7/36—Manufacture of hydraulic cements in general
    • 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
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/44—Burning; Melting
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    • 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
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Abstract

The invention discloses a process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization, which comprises the steps of obtaining phosphogypsum, drying, crushing, grinding, mixing with a ferro-silicoferrite raw material according to cement clinker with low KH value and low IM value, and grinding; the obtained mixture with low KH value and low IM value enters a desulfurization furnace through a preheater, and a carbonaceous raw material is added for CaSO 4 The desulfurization of (2); cooling the obtained desulfurized material, adding a calcareous raw material, an aluminum raw material and gypsum, and mixing and grinding to enable an IM value and a PM value to meet the standard requirements of the belite sulphoaluminate cement clinker; the mixture enters a decomposing furnace to decompose carbonate; calcining the decomposed raw materials in a rotary kiln to prepare belite sulphoaluminate cement clinker; the invention adopts a method of proportioning and desulfurizing with low KH value and simultaneously limiting IM value, realizes high-efficiency desulfurization of phosphogypsum and simultaneously limits Al 2 O 3 The influence of high content on the obvious inhibition effect of phosphogypsum desulfurization is developed, and a method for efficiently desulfurizing the phosphogypsum and preparing the belite sulphoaluminate cement clinker is developed.

Description

Process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to a process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization.
Background
The phosphogypsum is a solid waste produced in the production of phosphate fertilizer and phosphoric acid, and 4.5-5t of phosphogypsum is produced every 1t of phosphoric acid. The phosphogypsum is complex in composition, and besides calcium sulfate hydrate, the phosphogypsum also contains incompletely decomposed phosphate ores, residual phosphoric acid, fluoride, acid insoluble substances, organic matters and the like, wherein the existence of fluorine and the organic matters has the largest influence on the resource utilization of the phosphogypsum, the stacking can occupy a large amount of land, and the water resource and the land resource are polluted. According to the statistics of China phosphorus fertilizer industry Association, the total emission amount of phosphogypsum in 2020 years is about 7500-8000 million tons, although many industries try to use the phosphogypsum, the utilization rate is low, the domestic stock in China reaches more than 6 hundred million tons, more than 60 hundred million tons in the world, the phosphogypsum is recycled, safe and efficient, and the method has important significance for solving the problems of environmental pollution and resource waste caused by stacking treatment.
The phosphogypsum replaces limestone to be used as a CaO source to produce the cement clinker, which is a direction with challenge and significance for solving the resource utilization of the phosphogypsum, so that CaO in the clinker is mainly provided by the phosphogypsum, and the problem of carbon dioxide emission of the limestone in the cement production is reduced. However, caSO 4 Relative to CaCO 3 In other words, it needs to be completely decomposed and desulfurized at a higher temperature, which increases the operational difficulty and cost of the process, and even if it is present in large quantities at the clinker calcination temperature, it will bring many adverse effects to the production and application of the clinker, which will undoubtedly restrict its application in the cement clinker preparation.
The belite sulphoaluminate cement is prepared from
Figure BDA0003743921320000011
Mineral replaces C in portland cement 3 S and C 3 Mineral A for making up C 2 S has the defects of slow hydration in early stage and low strength, and is based on sulphoaluminate cement>
Figure BDA0003743921320000012
Low content of C 2 The cement has high S content, so that the cement has the characteristics of low consumption of calcareous raw materials, low firing temperature, short condensation time, high early strength, stable later strength development, micro-expansion and good corrosion resistance, and is low-carbon energy-saving cement. The solid waste phosphogypsum is adopted to replace limestone as a CaO source to prepare the belite sulphoaluminate cement clinker, so that the use amounts of the limestone, the natural gypsum and the desulfurized gypsum can be further reduced, and the solid waste phosphogypsum mainly plays two roles, namely, the desulfurized phosphogypsum becomes CaO to participate in the formation of all minerals, and the phosphogypsum without sulfur removal uses CaSO 4 Or other sulfur-containing substance is involved in>
Figure BDA0003743921320000013
In the formation of minerals. Therefore, the method is also suitable for occasions when the desulfurization rate of the phosphogypsum does not reach a higher level.
The application of the phosphogypsum to the preparation of cement clinker firstly needs desulfurization treatment, and the prior art has two routes, namely, the phosphogypsum is singly mixed with a reducing agent for desulfurization, so that the defects of low desulfurization efficiency and unstable desulfurization rate of products exist. Secondly, phosphogypsum, a ferro-silico-aluminum raw material and a reducing agent are mixed for desulfurization, but the phosphogypsum, the ferro-silico-aluminum raw material and the reducing agent have the defect of low desulfurization rate due to lack of related mechanisms and guidance methods, even are easy to melt and difficult to be used for production, especially for preparing Al 2 O 3 Belite sulphoaluminate cement clinker with higher content.
Disclosure of Invention
The invention aims to limit the IM value while adopting the method of proportioning and desulfurizing with low KH value, thereby realizing the efficient desulfurization of the phosphogypsum and limiting the Al value 2 O 3 The influence of high content on the obvious inhibition effect of phosphogypsum desulfurization is developed, and a method for efficiently desulfurizing the phosphogypsum and preparing the belite sulphoaluminate cement clinker is developed.
In order to achieve the purpose, the technical scheme is as follows:
a process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization comprises the following steps:
(1) Obtaining phosphogypsum, drying, crushing, grinding, mixing with a ferro-silicoferrite raw material according to a cement clinker with a low KH value and a low IM value, and grinding;
(2) The obtained mixture with low KH value and low IM value enters a desulfurization furnace through a preheater, and a carbonaceous raw material is added for CaSO 4 The desulfurization of (2);
(3) Cooling the obtained desulfurization material, adding a calcareous raw material, an aluminum raw material and gypsum, and mixing and grinding to ensure that the IM value and the PM value meet the standard requirements of the belite sulphoaluminate cement clinker; the mixture enters a decomposing furnace to decompose carbonate;
(4) And calcining the decomposed raw materials in a rotary kiln to obtain the belite sulphoaluminate cement clinker.
According to the scheme, SO in chemical components of phosphogypsum in the material preparation process in the step 1 3 The residual chemical components correspond to substances mainly containing CaO by calculating the loss on ignition per seAnd (4) measuring the quality.
According to the scheme, the ferro-silico-aluminum raw material in the step 1 is one or more of sand shale, coal gangue, silica, clay, fly ash, bauxite and various waste residues.
According to the scheme, the KH value in the step 1 is 0.60-0.70, and the IM value is not more than 5.00.
According to the scheme, the carbonaceous raw material in the step 2 is one or more of common coal, high-sulfur coal and coke; c in carbonaceous raw material and SO in phosphogypsum 3 Is 0.6 to 1.5.
According to the scheme, in the step 2, the desulfurization furnace creates a reducing atmosphere through the carbonaceous raw material and the introduced tertiary air; and controlling the volume concentration of CO in the desulfurizing furnace to be 2-6%.
According to the scheme, the desulfurization temperature of the desulfurization furnace in the step 2 is 1000-1100 ℃.
According to the scheme, the calcareous raw material in the step 3 is a raw material taking CaO as a main component, and specifically is one or a mixture of limestone, quicklime and hydrated lime; the aluminum raw material is Al 2 O 3 Raw materials as main components, specifically bauxite and the like; the gypsum is CaSO 4 The main component of the raw material is one or a mixture of phosphogypsum, desulfurized gypsum and natural gypsum.
According to the scheme, the KH value in the step 3 is set to be 0.60-0.70, the IM value is set to be 9.00-12.00, and the PM value is set to be 0.40-0.50.
According to the scheme, the calcining temperature of the rotary kiln in the step 4 is 1200-1325 ℃.
According to the scheme, the mineral composition of the belite sulphoaluminate cement clinker obtained in the step 4 is
Figure DA00037439213247531523
30% -40%, C 2 S is 45% -55%, C 4 AF 0% -8%, caSO 4 0% -7% of the total amount of the components and 0% of CaS.
The inventor finds out through research that C is 2 S can be formed in large quantities at 1000-1100 ℃ and SiO 2 Has high proportion in cement clinker, therefore SiO 2 Most advantageous to CaSO 4 Conversion of CaS to CaO and subsequent incorporation of SiO 2 Form C 2 And S, thereby stably and efficiently desulfurizing. SiO such as silica fume and rice husk ash 2 The highly reactive starting material also favors CaSO by this mechanism 4 And stably desulfurizing the CaS at low temperature. Al (Al) 2 O 3 Will promote CaSO from the side 4 Decomposition in the direction of CaO, but when CaSO 4 When decomposed to a certain degree, caSO is inhibited 4 Is mainly due to Al 2 O 3 Combined with CaSO 4 Form 3 CaO.3Al after reacting with CaO 2 O 3 ·CaSO 4 On the other hand, al 2 O 3 Will also directly react with C 2 S combines to form 2CaO SiO 2 ·Al 2 O 3 Thereby not playing a role of desulfurization, and striving for CaO in the system when the clinker is calcined at high temperature, if the CaSO is realized at low temperature 4 High decomposition rate and desulfurization rate of (1), in total, al 2 O 3 Is harmful.
Therefore, under the condition of adopting the high-efficiency stable desulfurization method of low KH, al required for preparing the belite sulphoaluminate cement clinker is obtained 2 O 3 Is higher in content of (A), and Al 2 O 3 The desulfurization effect of the phosphogypsum can be seriously influenced, so that the IM value is limited when low KH desulfurization is carried out, the mixture is prepared by adopting the low KH value and the low IM value when desulfurization is carried out, and the aluminum raw material is supplemented and calcined after the desulfurization meets the requirement, so that the negative influence on the desulfurization caused by excessive aluminum raw material is overcome, and the phosphogypsum is successfully applied to the preparation of belite sulphoaluminate cement clinker.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts the ingredients with low KH value to ensure that the phosphogypsum has good and stable desulfurization effect, and considers the Al of the belite sulphoaluminate cement clinker 2 O 3 The problem that the desulfurization effect of the phosphogypsum is adversely affected is high, and the IM value is limited, so that a method for efficiently desulfurizing the phosphogypsum and preparing the belite sulphoaluminate cement clinker is developed.
The phosphogypsum can be effectively utilized, caO in the clinker is mainly provided by the phosphogypsum, the percentage of the CaO provided by the phosphogypsum in the total CaO content is more than 65%, and the problem of carbon dioxide emission caused by limestone is reduced while the phosphogypsum solid waste is utilized.
Drawings
FIG. 1: the invention relates to a process flow chart for preparing belite sulphoaluminate cement clinker by desulfurization of phosphogypsum.
FIG. 2 is a schematic diagram: reduction of Al 2 O 3 Under the influence of (3), the XRD pattern of the desulfurized material with high and low KH values.
FIG. 3: XRD patterns of materials after desulfurization in examples 1 and 2.
FIG. 4 is a schematic view of: XRD patterns of the belite sulphoaluminate cement clinker obtained in examples 1, 2.
Detailed Description
The following examples further illustrate the technical solutions of the present invention, but should not be construed as limiting the scope of the present invention.
In a specific embodiment, a process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization is provided, which is shown in the attached figure 1:
(1) Obtaining phosphogypsum, drying, crushing, grinding, mixing with a ferro-silico-aluminum raw material according to a low KH value and a low IM value cement clinker, and grinding; SO in chemical components of phosphogypsum in the process of proportioning 3 The loss on ignition is calculated, and the remaining chemical components are measured in accordance with the substances mainly containing CaO.
(2) The obtained mixture with low KH value and low IM value enters a desulfurization furnace through a preheater, and a carbonaceous raw material is added for CaSO 4 The desulfurization of (2);
(3) Cooling the obtained desulfurization material, adding a calcareous raw material, an aluminum raw material and gypsum, and mixing and grinding to ensure that the IM value and the PM value meet the standard requirements of the belite sulphoaluminate cement clinker; the mixture enters a decomposing furnace to decompose carbonate;
(4) And calcining the decomposed raw materials in a rotary kiln to obtain the belite sulphoaluminate cement clinker.
Specifically, the aluminosilicoferrite raw material in the step 1 is one or more of sand shale, coal gangue, silica, clay, fly ash, bauxite and various waste residues. The KH value is 0.60-0.70, and the IM value is not more than 5.00.
Specifically, the carbonaceous raw material in the step 2 is one or more of common coal, high-sulfur coal and coke; c in carbonaceous raw material and SO in phosphogypsum 3 Is 0.6 to 1.5. The desulfurization temperature of the desulfurization furnace is 1000-1100 ℃. Creating a reducing atmosphere by using a carbonaceous raw material and introducing tertiary air; and controlling the volume concentration of CO in the desulfurizing furnace to be 2-6%.
Specifically, the calcareous raw material in the step 3 is a raw material taking CaO as a main component, and specifically is one or a mixture of limestone, quicklime and hydrated lime; the aluminum raw material is Al 2 O 3 Raw materials as main components, specifically bauxite and the like; the gypsum is CaSO 4 The main component of the raw material is one or a mixture of phosphogypsum, desulfurized gypsum and natural gypsum.
The standard requirement of belite sulphoaluminate cement clinker is that the KH value is set to 0.60-0.70, the im value to 9.00-12.00 and the pm value to 0.40-0.50.
Specifically, the calcination temperature of the rotary kiln in the step 4 is 1200-1325 ℃. Mineral composition of the resulting belite sulphoaluminate cement clinker C 4 A 3 S is 30% -40%, C 2 S is 45% -55%, C 4 AF 0% -8%, caSO 4 0% -7% of the total amount of the components and 0% of CaS.
The chemical components of the phosphogypsum, coal gangue, fly ash and bauxite used in the specific embodiment are shown in table 1:
TABLE 1 analysis of chemical composition
Figure BDA0003743921320000041
Figure BDA0003743921320000051
The carbonaceous feedstocks used were subjected to conventional analysis and chemical composition analysis of the ash, here high sulfur coal, with the results shown in tables 2 and 3, respectively:
TABLE 2 conventional analysis of high sulfur coal
Name(s) Moisture content Ash content Volatile component Fixed carbon content All sulfur Qnet,ad Qnet,d
High sulfur coal 1.42 23.48 10.25 64.85 2.99 25.25 26.33
TABLE 3 chemical composition analysis of ash content of high-sulfur coal
Name (R) Loss on ignition SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O Na 2 O
Ash content of coal 0 47.36 26.12 15.21 4.16 1.55 2.11 1.03 0.40
Example 1
1. Proportioning design of low KH value and low IM value
SO in chemical components of phosphogypsum 3 Calculated on its ownIn the loss on ignition, according to the loss on ignition of 20.04% +42.28% =62.32%, the rest chemical components are measured corresponding to substances mainly containing CaO, the loss on ignition is similar to the use of limestone, and the loss on ignition is designed and proportioned with a ferro-silico-aluminum raw material and a carbonaceous raw material according to cement clinker with low KH value and low IM value, wherein the carbonaceous raw material adopts high-sulfur coal, and the high-sulfur coal is mixed with SO in phosphogypsum according to the fixed carbon content 3 The molar ratio of (1) is 0.8, namely the usage amount of high-sulfur coal = phosphogypsum usage amount 0.4228 × 0.8 × 12/(80 × 0.6485), the ferro-silico-aluminum raw materials adopt coal gangue, fly ash and bauxite, and finally the weight ratio of phosphogypsum: coal gangue: fly ash: bauxite: the high-sulfur coal is 90:5:2:3:7.04, the weight of ash introduced by the high-sulfur coal is 7.04 × 0.2348=1.65, and the proportioning and theoretical mineral composition are shown in tables 4 and 5 respectively:
TABLE 4 compounding ratio
Name (R) Loss on ignition SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O Na 2 O Proportioning
Phosphogypsum 62.32 6.04 0.30 0.28 29.75 0.02 0 0.22 0.12 90
Coal gangue 4.63 76.3 6.62 4.64 1.91 2.35 0.48 1.34 0.55 5
Fly ash 5.33 43.41 32.88 6.44 6.72 0.7 1.2 0.81 0.47 2
Bauxite 0.43 7.67 84.03 1.73 0.43 0.16 0.05 0.78 0.03 3
Ash content of coal 0 47.36 26.12 15.21 4.16 1.55 2.11 1.03 0.40 1.65
TABLE 5 theoretical mineral composition for desulfurization
KH SM IM C 3 S C 2 S C 3 A C 4 AF CaSO 4
0.634 2.171 4.597 -9.20 77.52 21.25 6.16 0.32
KH of the mixture ratio of the low KH value and the low IM value is 0.634, IM is 4.597, and the main mineral phase is C 2 S is dominant and has no C 3 S。
2. Desulfurization of phosphogypsum
Mixing and grinding the phosphogypsum, the coal gangue, the fly ash and the bauxite which are measured according to the proportion, and then entering a desulfurization furnace through a preheater for CaSO 4 The desulfurization, the desulfurization furnace creates reducing atmosphere by adding metered high-sulfur coal and introducing tertiary air, and the temperature of the desulfurization furnace is set to 1100 ℃.
It should be noted that the speed or gas amount of the tertiary air introduced into the desulfurization furnace is influenced by the process and equipment, and the total sulfur analysis and detection of the desulfurized material are required to achieve the proper atmosphere conditionThe measured result is evaluated and adjusted, the lower the total sulfur content is, the better the total sulfur content is, the lower the total sulfur content is, the more the aluminum raw material is added in the mixture ratio of low KH value and low IM value, the lower the desulfurization effect of the phosphogypsum is caused and the CaSO is needed 4 For forming
Figure BDA0003743921320000061
This total sulfur analysis is converted to SO 3 The content of (A) can be widened to not more than 12%, and the volume concentration of CO in the desulfurization furnace is controlled to be 5% in the embodiment.
3. Adding calcium material, aluminum material and gypsum to adjust KH value and increase IM value and PM value
The calcium raw material, the aluminum raw material and the gypsum are added into the desulfurized material to be mixed and ground, the calcium raw material adopted is limestone, and the analysis result of the chemical components is shown in table 6:
TABLE 6 chemical composition analysis of limestone
Name (R) Loss on ignition SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O Na 2 O
Limestone 39.84 5.66 1.29 1.02 48.33 2.64 0.05 0.29 0.15
The bauxite and the phosphogypsum in the table 1 are respectively adopted as the aluminum raw material and the gypsum, the added limestone, bauxite and phosphogypsum adopt an external mixing method, namely the percentage of the total weight of the phosphogypsum, coal gangue, fly ash, bauxite and high-sulfur coal, and the mixing amount of the added limestone, bauxite and phosphogypsum is calculated by total sulfur analysis results, SO that the KH value is 0.60-0.70, the IM value is 9.00-12.00, the PM value is 0.40-0.50, and the PM value of sulfur-aluminum ratio = m (SO ratio is the ratio of sulfur to aluminum to the total sulfur to be analyzed) 3 )/(m(Al 2 O 3 )-0.64*m(Fe 2 O 3 ) SO if the results of the analysis of total sulfur 3 With a content of 0%, 17% limestone, 12% bauxite and 14% phosphogypsum are added, and the theoretical mineral composition obtained is shown in table 7:
TABLE 7 theoretical mineral composition of clinker
Figure BDA0003743921320000062
KH of 0.667, IM of 10.893, and PM of 0.439 were used here. And the mixed and ground powder enters a decomposing furnace through a preheater to decompose carbonate.
4. Calcination of clinker
And (3) calcining the decomposed raw materials in a rotary kiln to prepare the belite sulphoaluminate cement clinker, wherein the temperature of the rotary kiln is set to 1275 ℃.
Example 2
1. Proportioning design of low KH value and low IM value
SO in the chemical components of the phosphogypsum 3 Calculating the loss on ignition of the ardealite, according to the loss on ignition of 20.04% +42.28% =62.32%, measuring the rest chemical components corresponding to substances mainly containing CaO, similarly using limestone, and designing and proportioning the rest chemical components, a ferro-silico-aluminum raw material and a carbonaceous raw material according to a cement clinker with a low KH value and a low IM value, wherein the carbonaceous raw material adopts high-sulfur coal, and the high-sulfur coal is mixed with SO in the ardealite according to a fixed carbon content 3 The molar ratio of (1) is 0.8, namely the usage amount of high-sulfur coal = the usage amount of phosphogypsum 0.4228 0.8 12/(80 0.6485), the silicon-aluminum-iron raw material adopts coal gangue and fly ash, and finally the weight ratio of phosphogypsum: coal gangue: fly ash: the high-sulfur coal is 90:5:5:7.04, high sulfur coal introduced ash weight 7.04 × 0.2348=1.65, and the ratio and theoretical mineral composition are shown in tables 8 and 9, respectively:
TABLE 8 proportions
Name (R) Loss on ignition SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O Na 2 O Proportioning
Phosphogypsum 62.32 6.04 0.30 0.28 29.75 0.02 0 0.22 0.12 90
Coal gangue 4.63 76.3 6.62 4.64 1.91 2.35 0.48 1.34 0.55 5
Fly ash 5.33 43.41 32.88 6.44 6.72 0.7 1.2 0.81 0.47 5
Ash content of coal 0 47.36 26.12 15.21 4.16 1.55 2.11 1.03 0.40 1.65
TABLE 9 theoretical mineral composition for desulfurization
KH SM IM C 3 S C 2 S C 3 A C 4 AF CaSO 4
0.656 3.268 2.531 -3.40 80.19 11.76 7.13 0.45
The KH of the mixture ratio of the sub-low KH value and the low IM value is 0.656, the IM is 2.531, and the main mineral phase is C 2 S is dominant and has no C 3 S。
2. Desulfurization of phosphogypsum
Mixing and grinding the phosphogypsum, the coal gangue and the fly ash which are measured according to the proportion, and then entering a desulfurization furnace through a preheater for CaSO 4 The desulfurization is carried out, the desulfurization furnace creates a reducing atmosphere by adding metered high-sulfur coal and introducing tertiary air, and the temperature of the desulfurization furnace is set to 1090 ℃.
It should be noted here that the speed of the tertiary air or the gas amount introduced into the desulfurization furnace is influenced by the process and the equipment, and in order to achieve a proper atmosphere condition, the evaluation and adjustment are required to be performed through the total sulfur analysis and detection result of the desulfurized material, and the smaller the total sulfur content is, the better the total sulfur content is, the worse the desulfurization effect of the phosphogypsum is and the more CaSO is due to the excessive aluminum raw material added in the mixture ratio of low KH value and low IM value 4 For forming
Figure BDA0003743921320000071
This total sulfur analysis is converted to SO 3 The content of (A) can be widened to not more than 12%, and the volume concentration of CO in the desulfurization furnace is controlled to be 4% in the example.
3. Adding calcium material, aluminum material and gypsum to adjust KH value and increase IM value and PM value
Adding a calcium raw material, an aluminum raw material and gypsum into the desulfurized material for mixing and grinding, wherein the adopted calcium raw material is limestone, and the analysis results of chemical components are shown in table 10:
TABLE 10 chemical composition analysis of limestone
Name(s) Loss on ignition SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O Na 2 O
Limestone 39.84 5.66 1.29 1.02 48.33 2.64 0.05 0.29 0.15
The bauxite and the phosphogypsum in the table 1 are respectively adopted as the aluminum raw material and the gypsum, the added limestone, the bauxite and the phosphogypsum adopt an external doping method, namely the percentage of the total weight of the phosphogypsum, the coal gangue, the fly ash and the high-sulfur coal, the doping amount of the limestone, the bauxite and the phosphogypsum is calculated according to the total sulfur analysis result in the embodiment, the KH value is 0.60 to 0.70, the IM value is 9.00 to 12.00, the PM value is 0.40 to 0.50, the PM value of the sulfur-aluminum ratio is = m (SO ratio is more than m) 3 )/(m(Al 2 O 3 )-0.64*m(Fe 2 O 3 ) SO if the results of the analysis of total sulfur 3 With a content of 0%, using an external mix of 24% limestone, 14% bauxite and 14% phosphogypsum, the theoretical mineral composition obtained is shown in table 11:
TABLE 11 theoretical mineral composition of clinker
Figure BDA0003743921320000082
KH used this time was 0.670, IM was 9.341, and PM was 0.440. And the powder after mixed grinding enters a decomposing furnace through a preheater to decompose carbonate.
4. Calcination of clinker
And (3) calcining the decomposed raw materials in a rotary kiln to obtain the belite sulphoaluminate cement clinker, wherein the temperature of the rotary kiln is set to be 1300 ℃.
The inventor researches the desulfurization of phosphogypsum, and adopts the condition that the low KH is 0.666 and the high KH is 0.764 under the same other conditionsThe desulfurization effect was compared, the theoretical mineral composition is shown in Table 12, the XRD pattern is shown in FIG. 2, and CaSO is present in the combination with KH of 0.666 4 And a peak containing sulfur of substantially less than 0.764 of KH, and C 2 The peak of S is more obvious, and the result shows that the desulfurization effect is better due to the low KH ratio.
TABLE 12 theoretical mineral composition of the proportions used for desulfurization
KH SM IM C 3 S C 2 S C 3 A C 4 AF CaSO 4
0.764 2.710 1.444 27.07 49.32 7.83 11.16 0.25
0.666 2.717 1.404 -0.22 75.16 8.11 12.18 0.26
The IM values of examples 1 and 2 of the present invention were high, the theoretical mineral compositions are shown in Table 13, and the XRD patterns after desulfurization
As shown in FIG. 3, a higher IM results in a significant C 4 A 3 S、CaSO 4 And sulfur-containing peaks, wherein example 1 is more pronounced than example 2.
TABLE 13 theoretical mineral composition of the proportions used for desulfurization
Item KH SM IM C 3 S C 2 S C 3 A C 4 AF CaSO 4
Example 1 0.634 2.171 4.597 -9.20 77.52 21.25 6.16 0.32
Example 2 0.656 3.268 2.531 -3.40 80.19 11.76 7.13 0.45
The percentage of CaO in the total CaO content in the raw materials of the examples of the present invention is shown in table 14, and the XRD patterns of the belite sulphoaluminate cement clinker prepared in examples 1 and 2 are shown in fig. 4, and the minerals of each clinker are well formed. SO measurement in the Clinker of all examples 3 The content is not more than 9 percent, and the clinker is prepared at the calcining temperature of 1275 ℃; the CaO provided by the phosphogypsum accounts for more than 65 percent of the total CaO content, so the CaO in the belite sulphoaluminate cement clinker prepared by the invention is mainly provided by the phosphogypsum.
Al in desulfurization of low KH value and low IM value in examples 1 and 2 of the present invention 2 O 3 In different amounts, expressed as IM values, example 1 has the advantage that more is obtained
Figure BDA0003743921320000081
Meanwhile, the subsequent limestone is low in doping amount, and the defect is that Al is contained 2 O 3 The content of the phosphorus gypsum is higher, and the desulfurization rate of the phosphorus gypsum is reduced; the advantage of example 2 is that Al 2 O 3 Low content of (B), high desulfurization rate of phosphogypsum, and the defect that more->
Figure BDA0003743921320000091
The subsequent aluminum raw material and more limestone need to be supplemented; therefore, the ratio of the sulfur removal can be adjusted according to the actual conditions of the plant.
TABLE 14 percentage of CaO in the raw materials to the total CaO content
Figure BDA0003743921320000092
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.

Claims (5)

1. A process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization is characterized by comprising the following steps:
(1) Obtaining phosphogypsum, drying, crushing, grinding, mixing with a ferro-silicoferrite raw material according to a cement clinker with a low KH value and a low IM value, and grinding; the KH value is 0.60-0.70, and the IM value is not more than 5.00;
(2) The obtained mixture with low KH value and low IM value enters a desulfurization furnace through a preheater, and a carbonaceous raw material is added for CaSO 4 The desulfurization of (2); the carbonaceous raw material is one or more of common coal, high-sulfur coal and coke; c in carbonaceous raw material and SO in phosphogypsum 3 The molar ratio of (A) is 0.6-1.5; the desulfurization furnace creates a reducing atmosphere by a carbonaceous raw material and introducing tertiary air; controlling the volume concentration of CO in the desulfurizing furnace to be 2-6%; the desulfurization temperature of the desulfurization furnace is 1000-1100 ℃;
(3) Cooling the obtained desulfurization material, adding a calcareous raw material, an aluminum raw material and gypsum, and mixing and grinding to ensure that the IM value and the PM value meet the standard requirements of the belite sulphoaluminate cement clinker; the mixture enters a decomposing furnace to decompose carbonate; KH value is set to 0.60-0.70, IM value is set to 9.00-12.00, PM value is set to 0.40-0.50;
(4) And calcining the decomposed raw materials in a rotary kiln to obtain the belite sulphoaluminate cement clinker.
2. The process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization according to claim 1, wherein the aluminosilicoferrite raw material in the step 1 is one or more of sand shale, coal gangue, silica, clay, fly ash, bauxite and various waste residues.
3. The process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization according to claim 1, wherein the calcareous raw material in the step 3 is a raw material taking CaO as a main component, and specifically is one or a mixture of limestone, quicklime and hydrated lime; the aluminum raw material is Al 2 O 3 A raw material as a main component, specifically bauxite; the gypsum is CaSO 4 The main component of the raw material is one or a mixture of phosphogypsum, desulfurized gypsum and natural gypsum.
4. The process for preparing belite sulphoaluminate cement clinker by phosphogypsum desulfurization according to claim 1, wherein the calcination temperature of the rotary kiln in step 4 is 1200-1325 ℃.
5. The process for preparing the belite sulphoaluminate cement clinker by desulfurization of the phosphogypsum according to claim 1, wherein the mineral composition of the belite sulphoaluminate cement clinker obtained in step 4 is the same as that of the phosphogypsum
Figure QLYQS_1
30% -40%, C 2 S is 45% -55%, C 4 AF 0% -8%, caSO 4 Is 0 to 7% and CaS is 0%. />
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