CN106698988B - A kind of phosphogypsum modified with carbonate rock and preparation method thereof - Google Patents

Abstract

The invention relates to a carbonate rock modified phosphogypsum and a preparation method. The natural alkaline carbonate rock is pulverized and then mixed and stirred with the phosphogypsum, water is added at the same time, and after stirring evenly, it is aged for a certain time to make the aqueous solution pH When the value is neutral, the modified phosphogypsum can be made by dehydration and drying. Compared with the prior art, the present invention utilizes natural alkaline carbonate rock and its tailings to modify phosphogypsum, the method is simple, has no secondary pollution, does not need links such as granulation, high temperature, wet grinding, etc. It has the advantages of low consumption, low cost, abundant raw material resources and low price. When the modified phosphogypsum prepared by this method is used as a cement retarder, under the premise that the setting time meets the standard requirements of "General Portland Cement", compared with the cement prepared from natural gypsum or desulfurized gypsum, it can improve the The cement strength is more than 10%, and it has good adaptability with polycarboxylate superplasticizers.

Description

A kind of phosphogypsum modified with carbonate rock and preparation method thereof

Technical field:

The invention belongs to the field of building materials and environmental pollution control, and relates to the comprehensive utilization of industrial wastes, in particular to the utilization of industrial waste residues for wet production of phosphate fertilizers or phosphoric acid, in particular to the utilization of alkaline carbonate rocks to modify phosphogypsum and preparation method.

Background technique:

Phosphogypsum is an industrial by-product of the wet production of phosphoric acid in the phosphating industry. Its main chemical component is dihydrate gypsum (CaSO ₄ 2H ₂ O), generally its content is as high as 90%, and contains a small amount of impurities such as phosphorus, fluorine and organic matter. Its content is closely related to the mineral composition of phosphate rock and the specific production process. At present, the annual discharge of phosphogypsum in my country exceeds 50 million tons, but the utilization rate is only about 20%. A large amount of phosphogypsum can only be stored as waste. resources, and will cause serious pollution to the environment. Phosphogypsum is similar to natural gypsum or desulfurized gypsum in structure and chemical composition, so it can theoretically replace natural gypsum or desulfurized gypsum as cement retarder. However, compared with natural gypsum or desulfurized gypsum, the problems of phosphogypsum directly used as cement retarder are: 1) it will prolong the setting time of cement by 3-4 hours; 2) it will reduce the strength of cement, especially the reduction of early strength is relatively Obviously; 3) the dosage of polycarboxylate superplasticizer will be increased. Therefore, phosphogypsum should not be used directly as a cement retarder. If it is used as a cement retarder, the phosphogypsum must be modified in advance to remove the harm of harmful acids, so that the setting time and early stage of the modified phosphogypsum cement can be improved. The strength and compatibility with polycarboxylate superplasticizers can reach the level of natural gypsum cement or desulfurized gypsum cement, which has become the technical key to the production of modified phosphogypsum cement.

At present, there are many physical and chemical methods for modification of phosphogypsum, such as water washing method, screening method, flash burning method, ball milling method, lime neutralization method, general Portland cement method, etc., but these methods do not exist. The problem of secondary pollution is the complex process, high energy consumption and high cost, which is the fundamental reason for the low consumption of phosphogypsum in the cement industry. Among these pretreatment methods of modified phosphogypsum, lime neutralization method and general Portland cement neutralization method have the advantages of relatively simple process, relatively low energy consumption and cost compared with other methods.

CN103833254A discloses a "modification method of phosphogypsum used as a cement retarder". The phosphogypsum and lime are mixed and granulated in a ratio of 1000:60, and then the granules are placed at a temperature of 40 to 50 ° C. Under curing for 7-10 days, the prepared modified phosphogypsum can be used as cement retarder. The modification method is to neutralize the harmful acid in the phosphogypsum by using the hydration and alkaline properties of quicklime or slaked lime, so that the soluble phosphorus and fluorine in the phosphogypsum are converted into insoluble inert salts. Although the process is relatively simple, this method has the following shortcomings: 1) granulation is required, and the high temperature and maturation period are long; 2) the price of lime is high and the modification cost is high.

CN102745926A discloses a kind of "modified phosphogypsum and its preparation method". The general Portland cement used for modified phosphogypsum should be determined in advance to meet the needs of producing different varieties of general Portland cement. , the modification method is to add a small amount of general Portland cement into the phosphogypsum, then add water to mix wet grinding, and age for more than 8 hours. The prepared modified phosphogypsum can be used as a cement retarder. The modification method is to use the universal Portland cement hydration product calcium hydroxide Ca(OH) ₂ to neutralize the harmful acid in the phosphogypsum, so that the soluble phosphorus and fluorine in the phosphogypsum are converted into insoluble inert salts. Although this method is simple in process, it still has the following shortcomings: 1) When phosphogypsum is modified, wet grinding needs to be carried out after phosphogypsum, general Portland cement and water are mixed. 2) The high price of cement and the high cost of wet grinding make the modification cost high.

CN104310836A discloses a kind of "modified phosphogypsum and its preparation method and use", which is prepared by using phosphogypsum, papermaking white mud and kiln dust as raw materials, and makes full use of industrial waste residue. The preparation method of the modified phosphogypsum of the present invention includes the following steps: Treatment methods such as water washing, flotation, alkaline neutralization and modification can get rid of the shortcomings of other natural minerals and chemical raw materials required for modifiers in the past, but the process is relatively complex and the source of raw materials is narrow, resulting in high cost of modified phosphogypsum.

CN105347711A discloses a "modified phosphogypsum and its preparation method". In an inert gas atmosphere, the phosphogypsum is calcined at a flue gas temperature of 900-1100 ° C for 1-5 hours to obtain a product. Because high temperature treatment is required, As a result, the cost of modified phosphogypsum is high.

CN1211309C discloses a kind of "modified phosphogypsum and its preparation" which uses other waste residue and waste liquid as additives to produce a modified phosphogypsum of cement retarder and cement enhancer and its preparation. Its main components are: aluminum sulfate slag, alum stone, plant ash, bentonite, slag, dickite, waste liquid waste from paper mills and alkali plants, 1, 2 or 3 kinds of white mud and sepiolite) 10-30 %, phosphogypsum 70-90%. Mix 70-90% phosphogypsum with 10-30% additives in a weight ratio, and stack them at a certain temperature to obtain modified phosphogypsum. After drying, the ash-forming cement retarder can become a cement reinforcing agent if the modified phosphogypsum that is sultry for 8-24 hours is calcined at a high temperature of 600-900 °C. However, due to the complex process, the alkaline substances used for the modification of phosphogypsum are the waste liquid and waste residue of the alkali plant. In particular, high temperature calcination at 600-900°C is required, resulting in high cost and narrow source of raw materials, so it does not have wide applicability.

Invention content:

The object of the present invention is to aim at the deficiencies of the above-mentioned prior art, by providing a new modified phosphogypsum and a preparation method thereof, so that the cement setting time prepared by using the modified phosphogypsum can reach the time required for preparing cement with natural gypsum or desulfurized gypsum. It can also improve the strength of cement by more than 10%, and the cement has good adaptability with polycarboxylate superplasticizers.

The material used for the modification of the phosphogypsum in the present invention is alkaline carbonate rock, such as natural limestone, dolomite, magnesite and its tailings, etc., so the preparation process is simple, the modification cost is low, the source of raw materials is wide, and the effect is good feature.

The purpose of this invention is to realize through the following technical solutions:

A modified phosphogypsum using alkaline carbonate rock, its components are made by mixing the following raw materials:

Phosphogypsum 70-80%

Carbonate powder 20-30%

Water 100-140%, including free water in phosphogypsum.

The phosphogypsum is the industrial waste residue of wet production of phosphate fertilizer or phosphoric acid.

The alkaline carbonate rock powder is limited to limestone, dolomite, magnesite and tailings.

The fineness of carbonate rock powder, if the specific surface area is used, can be controlled within the range of 300-400m ² /kg,

A preparation method of modified phosphogypsum with carbonate rock, comprising the following steps:

a. Pulverize the carbonate rock to a specific surface area of 300-400m ² /kg;

b. Put 20-30% carbonate rock powder and 70-80% phosphogypsum in a mixer by mass percentage and stir for 3-5 minutes;

c. Inject 100-140% water of the total mass of phosphogypsum and carbonate rock powder while stirring;

d. After adding water and mixing evenly, aging for more than 6 hours;

e. After drying, it is modified phosphogypsum.

Beneficial effect: compared with the prior art, the present invention uses alkaline substances to neutralize harmful acids in phosphogypsum, so that soluble phosphorus and fluorine are converted into insoluble salts; the difference is that natural alkaline carbonic acid is used. Salt rock and tailings modified phosphogypsum has the characteristics of low material price and wide source. Compared with the cement prepared from natural gypsum and the cement prepared from desulfurized gypsum, the cement prepared from modified phosphogypsum can satisfy the existing silicic acid in setting time. Under the premise of salt cement, the compressive strength of cement can be increased by more than 10%, and it has good adaptability with polycarboxylate superplasticizers. The comparison of the performance test results of strength, setting time, mortar fluidity, etc. between the cement prepared with different alkaline carbonate modified phosphogypsum and the original phosphogypsum, desulfurized gypsum, and ordinary gypsum is shown in the following table:

Test results of cement strength, setting time and mortar fluidity of different gypsum preparations

Detailed ways:

Below in conjunction with embodiment, the present invention is described in further detail:

A modified phosphogypsum using carbonate rock, its components are made by mixing the following raw materials:

Phosphogypsum 70-80%

Alkaline carbonate rock powder 20-30%

Water 100-140%, including free water in phosphogypsum.

The phosphogypsum is the industrial waste residue of wet production of phosphate fertilizer or phosphoric acid. The carbonate rock powder is limited to limestone, dolomite, magnesite and tailings. For carbonate rock powder, the specific surface area should be in the range of 300-400m ² /kg.

A preparation method of modified phosphogypsum with carbonate rock, comprising the following steps:

a. Pulverize the carbonate rock to a specific surface area of 300-400m ² /kg;

b. Put 20-30% carbonate rock powder and 70-80% phosphogypsum in a mixer by mass percentage and stir for 3-5 minutes;

c. Add 100-140% water of the total mass of phosphogypsum and carbonate rock powder while stirring;

d. After adding water and mixing evenly, aging for more than 6 hours;

e. After drying, it is modified phosphogypsum.

Example 1

Take 8.0Kg of phosphogypsum from Liaoning Xiyang Special Fertilizer Co., Ltd., mix it with 2.0Kg of Jilin rock limestone crushed to 320m ² /kg, add 12.0Kg of water to make a modified phosphogypsum slurry, and measure the aging time for 7 hours PH=7.0/7.5, it is modified phosphogypsum after drying.

Preparation of Portland cement: take 4.75Kg of cement clinker from Jidong Cement Jilin Co., Ltd. and grind it with a cement experimental mill. While grinding the cement clinker, add 0.25Kg of the above-mentioned modified phosphogypsum.

The strength of cement is tested according to GB/T 17671 standard, and the setting time of cement is tested according to GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate superplasticizer, 1% polycarboxylate superplasticizer was added in the preparation of mortar, and the fluidity of cement mortar was tested according to GB/T 2419-2005 standard.

Embodiment 1 Cement performance test results

Example 2

Dry the desulfurized gypsum to constant weight.

To prepare Portland cement, take 4.65Kg of cement clinker from Jidong Cement Jilin Co., Ltd. and add 0.35Kg of desulfurized gypsum while grinding the cement clinker.

The strength of cement is tested according to GB/T 17671 standard, and the setting time of cement is tested according to GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate superplasticizer, 1% polycarboxylate superplasticizer was added in the preparation of mortar, and the fluidity of cement mortar was tested according to GB/T 2419-2005 standard.

Embodiment 2 Cement performance test results

Example 3

Take 7.0Kg of phosphogypsum, take 3.0Kg of Liaoning Dashiqiao magnesite powder that is pulverized and ground to 330m ² /kg and mix well, add 130Kg of water to make modified phosphogypsum slurry, and measure PH=6.0 after aging time for 7.5 hours /7.0, which is modified phosphogypsum.

To prepare Portland cement, take 4.6Kg of cement clinker from Jidong Cement Jilin Co., Ltd., add 0.4Kg of the above modified phosphogypsum while grinding the cement clinker,

The strength of cement is tested according to GB/T 17671 standard, and the setting time of cement is tested according to GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate superplasticizer, 1% polycarboxylate superplasticizer was added in the preparation of mortar, and the fluidity of cement mortar was tested according to GB/T 2419-2005 standard.

Embodiment 3 Cement performance testing results

Example 4

Take 8.2Kg of phosphogypsum, take 1.8Kg of Liaoning Haicheng magnesite tailings crushed and ground to 340m ² /kg, mix well, add 130Kg of water to make modified phosphogypsum slurry, aging time is 14.0 hours, Ph=6.5 /7.0 is modified phosphogypsum.

To prepare Portland cement, take 4.6Kg of cement clinker from Jidong Cement Jilin Co., Ltd. and add 0.4Kg of magnesite-modified phosphogypsum while grinding the cement clinker.

The strength of cement is tested according to GB/T 17671 standard, and the setting time of cement is tested according to GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate superplasticizer, 1% polycarboxylate superplasticizer was added in the preparation of mortar, and the fluidity of cement mortar was tested according to GB/T 2419-2005 standard.

Embodiment 4 Cement performance test result

Example 5

Take the undisturbed phosphogypsum from Liaoning Xiyang Special Fertilizer Co., Ltd. and dry it to a constant state.

To prepare Portland cement, take 4.72Kg of cement clinker from Jidong Cement Jilin Co., Ltd., and add 0.28Kg of undisturbed phosphogypsum while grinding the cement clinker.

The strength of cement is tested according to GB/T 17671 standard, and the setting time of cement is tested according to GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate superplasticizer, 1% polycarboxylate superplasticizer was added in the preparation of mortar, and the fluidity of cement mortar was tested according to GB/T 2419-2005 standard.

Embodiment 5 Cement performance testing results

Example 6

Take 7.5Kg of phosphogypsum from Liaoning Xiyang Special Fertilizer Co., Ltd., take 2.5Kg of Jilin Pan Limestone crushed and ground to 370m ² /kg, mix well, add 12.0Kg of water to make modified phosphogypsum slurry, and measure after aging for 13.0 hours. PH = 6.2/7.6, drying is modified phosphogypsum.

Preparation of Portland cement: take 4.725Kg of cement clinker from Jidong Cement Jilin Co., Ltd., and take 0.275Kg of the above-mentioned modified gypsum, and grind them in a cement experiment. The measured cement strength, setting time and mortar fluidity are shown in the table below.

Embodiment 6 Cement performance testing results

It can be seen from the above examples that the cement prepared from modified phosphogypsum has similar early strength compared with cement prepared from desulfurized gypsum and cement prepared from ordinary gypsum, but the strength at 28 days can be as high as 10% or more.

Claims (2)

1. a preparation method with carbonate rock modified phosphogypsum, is characterized in that, comprises the following steps: a. Pulverize the carbonate rock to a specific surface area of 300-400 m ² /kg; b. Put 20-30% carbonate rock powder and 70-80% phosphogypsum in a mixer by mass percentage and stir for 3-5 minutes; c. Inject 100-140% water of the total mass of phosphogypsum and carbonate rock powder while stirring; d. After adding water and mixing evenly, aging for more than 6 hours; e. After drying, it is modified phosphogypsum; The carbonate rock powder is dolomite, magnesite and tailings. 2. according to a kind of preparation method of carbonate rock modified phosphogypsum according to claim 1, it is characterized in that, described phosphogypsum is the industrial waste residue of wet production of phosphate fertilizer or phosphate.