CN106698988A - Carbonatite-modified phosphogypsum , and preparation method of carbonatite-modified phosphogypsum - Google Patents

Abstract

The invention relates to a modified phosphogypsum with carbonate rock and a preparation method thereof. The natural alkaline carbonate rock is ground and mixed with the phosphogypsum, and water is added at the same time. When the value is neutral, the modified phosphogypsum can be made by dehydration and drying. Compared with the prior art, the present invention uses natural alkaline carbonate rock and its tailings to modify phosphogypsum, the method is simple, no secondary pollution, no granulation, high temperature and wet grinding, etc. It has the advantages of low consumption, low cost, rich and extensive raw material resources and low price. When the modified phosphogypsum prepared by this method is used as a cement retarder, on the premise that the setting time meets the standard requirements of "General Portland Cement", compared with the cement prepared by natural gypsum or desulfurized gypsum, it can improve The cement strength is more than 10%, and it has good adaptability with polycarboxylate water reducer.

Description

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

Technical field:

The invention belongs to the field of building materials and environmental pollution control. The invention relates to the comprehensive utilization of industrial waste, in particular to the utilization of industrial waste slag produced by wet method of phosphate fertilizer or phosphoric acid, especially the use of alkaline carbonate rock to modify phosphogypsum and preparation method.

Background technique:

Phosphogypsum is an industrial by-product of phosphoric acid produced by wet process in phosphating industry. Its main chemical composition is dihydrate gypsum (CaSO ₄ ·2H ₂ O), generally its content is as high as 90%, and it 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, and its cumulative stockpiles have exceeded 200 million tons, which not only takes up a lot of land resources, but also 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 a cement retarder. However, compared with natural gypsum or desulfurized gypsum, the problems of using phosphogypsum directly as a 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 early strength reduction is relatively Obviously; 3) It will increase the amount of polycarboxylate superplasticizer. 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 harmful acid in it, so that the setting time of the modified phosphogypsum cement, the early The strength and adaptability to polycarboxylate water reducers reach the level of natural gypsum cement or desulfurized gypsum cement, which has become the key technology for the production of modified phosphogypsum cement.

At present, there are many physical and chemical methods for modifying phosphogypsum, such as water washing purification method, sieving 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 that there are problems such as complex process, high energy consumption and high cost, which is the root cause of the current cement industry's low consumption of phosphogypsum. 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", mixing phosphogypsum and lime at a ratio of 1000:60 to granulate, and then placing the granules at a temperature of 40-50°C The prepared modified phosphogypsum can be used as a cement retarder after aging for 7-10 days. The modification method is to neutralize the harmful acid in phosphogypsum by using the characteristic of quicklime or slaked lime to show alkalinity after hydration, so that the soluble phosphorus and fluorine in phosphogypsum are converted into insoluble inert salts. Although the process of this method is relatively simple, the disadvantages are: 1) granulation is required, high temperature and long curing period; 2) the price of lime is high and the cost of modification is relatively high.

CN102745926A discloses a "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 types of general portland cement , the modification method is to mix a small amount of general-purpose Portland cement in phosphogypsum, then add water to mix and wet grind, 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 general-purpose 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 the process is simple, the method still has the following disadvantages: 1) when phosphogypsum is modified, wet grinding is required after mixing phosphogypsum, general Portland cement and water. 2) The price of cement is high, and the cost of wet grinding is high, which makes the cost of modification higher.

CN104310836A discloses a "modified phosphogypsum and its preparation method and use", which is prepared from phosphogypsum, papermaking white mud and kiln dust, and fully utilizes industrial waste residues. The preparation method of modified phosphogypsum of the present invention includes Treatment methods such as water washing, flotation, alkaline neutralization and modification can get rid of the shortcomings of modifiers requiring other natural minerals and chemical raw materials in the past, but the process is relatively complicated 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, phosphogypsum is calcined at a flue gas temperature of 900-1100°C for 1-5 hours to obtain a product. Due to the need for high-temperature treatment, Lead to high cost of modified phosphogypsum.

CN1211309C discloses a modified phosphogypsum and its preparation in "Modified Phosphogypsum and Its Preparation", which uses other waste slag and waste liquid as additives to produce cement cement retarder and cement reinforcing agent. Its main components are: aluminum sulfate slag, alunite, plant ash, bentonite, slag, dickite, waste liquid and residue from paper mills and alkali plants, 1, 2 or 3 of white mud and sepiolite) 10-30 %, Phosphogypsum 70-90%. Mix 70-90% phosphogypsum and 10-30% additives by weight and stack them in a certain temperature to make modified phosphogypsum. After drying, it becomes a gray cement retarder. If the modified phosphogypsum is calcined at a temperature of 600-900°C for 8-24 hours, it can become a cement reinforcing agent. 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 sources of raw materials, so it does not have wide applicability.

Invention content:

The purpose of the present invention is to address the above-mentioned deficiencies in the prior art, by providing a new modified phosphogypsum and a preparation method thereof, so that the setting time of cement prepared by using modified phosphogypsum reaches that of preparing cement with natural gypsum or desulfurized gypsum. It can also increase the strength of cement by more than 10%, and the cement has good adaptability to polycarboxylate water reducers.

The material used in the modification of phosphogypsum in the present invention is alkaline carbonate rock, such as natural limestone, dolomite, magnesite and its tailings, etc., so it has the advantages of simple preparation process, low modification cost, wide source of raw materials, and effective nice features.

The purpose of the present invention is achieved through the following technical solutions:

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

Phosphogypsum 70-80%

Carbonate rock powder 20-30%

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

The phosphogypsum is the industrial waste residue produced by wet method to produce phosphate fertilizer or phosphoric acid.

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

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

A preparation method for modifying phosphogypsum with carbonate rock, comprising the following steps:

a. Crush the carbonate rock until the specific surface area is 300-400m ² /kg;

b. Put 20-30% carbonate rock powder and 70-80% phosphogypsum into the mixer according to mass percentage and stir for 3-5 minutes;

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

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

e. Modified phosphogypsum after drying.

Beneficial effects: Compared with the prior art, the present invention uses alkaline substances to neutralize harmful acids in phosphogypsum, and converts soluble phosphorus and fluorine into insoluble salts; the difference lies in the use of natural alkaline carbonic acid Salt rock and tailings modified phosphogypsum has the characteristics of low material price and wide range of sources. Compared with cement prepared from natural gypsum and cement prepared from desulfurized gypsum, the setting time of cement prepared from modified phosphogypsum meets the requirements of existing silicic acid. Under the premise of salt cement, it can increase the compressive strength of cement by more than 10%, and has good adaptability with polycarboxylate water reducer. The comparison of performance test results of strength, setting time, and fluidity of mortar and sand between cement prepared by using different alkaline carbonate modified phosphogypsum and cement prepared by original phosphogypsum, desulfurized gypsum, and ordinary gypsum is shown in the table below:

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

detailed description:

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 produced by wet method to produce 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 within the range of 300-400m ² /kg.

A preparation method for modifying phosphogypsum with carbonate rock, comprising the following steps:

a. Crush the carbonate rock until the specific surface area is 300-400m ² /kg;

b. Put 20-30% carbonate rock powder and 70-80% phosphogypsum into the mixer according to mass percentage and stir for 3-5 minutes;

c, add phosphogypsum and carbonate rock powder total mass 100-140% water while stirring;

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

e. Modified phosphogypsum after drying.

Example 1

Take 8.0Kg of phosphogypsum from Liaoning Xiyang Special Fertilizer Co., Ltd., mix it evenly with 2.0Kg of Jilin Panshi limestone crushed to 320m ² /kg, add 12.0Kg of water to make modified phosphogypsum slurry, and measure it with an aging time of 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., grind it with a cement experimental mill, and add 0.25Kg of the above-mentioned modified phosphogypsum while grinding the cement clinker.

Test the cement strength according to the GB/T 17671 standard, and test the cement setting time according to the GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate water reducer, 1% polycarboxylate water reducer 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 detection result

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.

Test the cement strength according to the GB/T 17671 standard, and test the cement setting time according to the GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate water reducer, 1% polycarboxylate water reducer 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 detection result

Example 3

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

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

Test the cement strength according to the GB/T 17671 standard, and test the cement setting time according to the GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate water reducer, 1% polycarboxylate water reducer 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 detection result

Example 4

Take 8.2Kg of phosphogypsum, take 1.8Kg of Liaoning Haicheng magnesite tailings crushed 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.

Prepare Portland cement, get 4.6Kg of cement clinker of Jidong Cement Jilin Co., Ltd., while grinding the cement clinker, add 0.4Kg of magnesite modified phosphogypsum,

Test the cement strength according to the GB/T 17671 standard, and test the cement setting time according to the GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate water reducer, 1% polycarboxylate water reducer 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 detection result

Example 5

Take the original phosphogypsum from Liaoning Xiyang Special Fertilizer Co., Ltd. and dry it until constant.

Prepare Portland cement, get Jidong Cement Jilin Co., Ltd. cement clinker 4.72Kg, while grinding cement clinker, add original state phosphogypsum 0.28Kg,

Test the cement strength according to the GB/T 17671 standard, and test the cement setting time according to the GB/T750 standard. In order to verify the adaptability of modified phosphogypsum and polycarboxylate water reducer, 1% polycarboxylate water reducer 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 detection result

Example 6

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

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

Embodiment 6 cement performance detection result

It can be seen from the above examples that the early strength of cement prepared from modified phosphogypsum is similar to cement prepared from desulfurized gypsum and cement prepared from ordinary gypsum, but the strength at 28 days can be as high as 10%.

Claims (5)

1. one kind uses carbonate rock modified ardealite, it is characterised in that its component is mixed by following raw materials according：

Ardealite 70~80%

Carbonate rock powder 20~30%

Water 100~140%, including the Free water in ardealite.

2. use carbonate rock modified ardealite according to the one kind described in claim 1, it is characterised in that described ardealite, be The industrial residue of wet production phosphate fertilizer or phosphoric acid.

3. carbonate rock modified ardealite is used according to the one kind described in claim 1, it is characterised in that described carbonate rock powder It is only limitted to lime stone, dolomite and magnesite and mine tailing.

4. carbonate rock modified ardealite is used according to the one kind described in claim 1, it is characterised in that carbonate rock powder, should In 300~400m²In the range of/kg.

5. according to a kind of preparation method of the use carbonate rock modified ardealite described in claim 1, it is characterised in that including with Lower step：

A, carbonate rock is crushed to 300~400m of specific surface area²/kg；

B, 20~30% carbonate rock powders and 70~80% ardealites are put into 3~5 are stirred in mixer by mass percentage Minute；

C, the water for injecting ardealite and carbonate rock powder gross mass 100~140% simultaneously in stirring；

D, be mixed with water after, be aged more than 6 hours；

E, after drying be modified ardealite.