CN1159250C - Modified phosphogypsum brick and its application as cement retarder - Google Patents

Abstract

The present invention relates to a denatured ardealite brick and the application of the denatured ardealite brick used as a cement retardant. The denatured ardealite brick contains 80 to 95 wt% of ardealite, 2 to 15 wt% of reinforcing agent, and 3 to 10 wt% of denatured agent. A mixture of 100 wt% of the sum of the component quantity is moulded and naturally dried. The denatured ardealite brick has the water content of smaller than 10 wt%, the SO3 of larger than 35 wt%, the pH of larger than 7 and the P2O5 of smaller than 0.1 wt%. The denatured ardealite brick is convenient for storage and transportation and can replace natural dihydrate gypsum or anhydrite to be used as the retardant for cement production. The use performance of the present invention completely reaches the requirement of the cement production, and the denatured ardealite brick can reduces the production cost of cement and enhances cement performance.

Description

Modified phosphogypsum brick and its application as cement retarder

technical field

The invention relates to the utilization technology of phosphogypsum, a by-product of phosphorus chemical industry, in particular to the application of phosphogypsum modified into bricks and used as a cement retarder.

Background technique

Phosphogypsum is industrial waste slag discharged during the production process of phosphorus chemical enterprises. The current stacking not only takes up a lot of space and funds, but also pollutes the environment. The main components in phosphogypsum are the same as natural dihydrate gypsum. In cement production, natural gypsum is used as a retarder to make the performance of the factory cement meet the national standard. Natural gypsum is more expensive from mining to entering the factory; in addition, some cement needs to be mixed with slag and other admixtures, but the early strength of the admixture is low and the amount of admixture is limited, which makes the cost of cement production high. Using phosphogypsum to prepare modified phosphogypsum bricks instead of natural gypsum as a cement retarder has a low price, can increase cement strength, reduce cement production costs, and increase cement enterprise profits. The production of modified phosphogypsum bricks also solves the problem of waste slag stacking in chemical companies, saves money for phosphorus chemical companies, and also comprehensively manages the environment. Obviously, the modification of phosphogypsum instead of natural gypsum has obvious economic and social benefits.

Modified phosphogypsum "bricks" are different from phosphogypsum "balls". Phosphogypsum has a large water content. The balls made of phosphogypsum are not easy to be ventilated and dried, and the water content of the balls is high. It is easy to cause cement agglomeration and blockage in cement production and use. Phosphogypsum bricks are easy to ventilate and dry, so that the water content of modified phosphogypsum is small, and it can be used like natural gypsum in cement production without causing adverse effects.

Contents of the invention

The purpose of the present invention is to modify the phosphogypsum waste residue discharged by phosphorus chemical enterprises, provide a modified phosphogypsum brick and its application as a cement retarder.

The modified phosphogypsum brick to achieve the purpose of the present invention is a mixture containing 80-95wt% phosphogypsum, 2-15wt% reinforcing agent, 3-10wt% modifying agent component, and the sum of each component is 100wt%. Made by natural drying, the modified phosphogypsum brick has a water content _of <10wt%, SO ₃ >35wt%, and soluble _P2O3 <0.1wt%.

The reinforcing agent is any one or more of blast furnace slag, fly ash, steel slag or other industrial waste slag.

The 3-10wt% modifier is 0-10wt% alkaline substance: any one or two of calcium carbide slag, alkali slag, white mud, cement, lime, red mud, and 0-10wt% industrial Aluminum slag or alunite or calcined bauxite.

The preparation method of the modified phosphogypsum brick is made by mixing materials according to the above-mentioned ingredient ratio, stirring and mixing, extrusion molding and natural drying.

The prepared modified phosphogypsum brick has a water content of <10wt%, _SO3 >35wt%, soluble _P2O5 < _0.1wt %, and pH>7.

The modified phosphogypsum brick can completely replace the natural gypsum as a cement retarder, and the added amount is 4-8wt% of the cement weight. Compared with the natural gypsum, it can also improve the physical property index of the produced cement, especially the cement strength.

Detailed ways

The batching of the modified phosphogypsum bricks should be carried out according to the content of soluble P ₂ O ₅ in the original phosphogypsum, and the key point of adjustment should be to make the soluble P ₂ O ₅ in the prepared modified phosphogypsum bricks <0.1wt%.

Preparation example

Example 1

Take 94 parts of phosphogypsum, 3 parts of lime, and 3 parts of slag according to the weight ratio, mix and stir the ingredients evenly, extrude them into bricks, and dry them naturally at room temperature to obtain modified phosphogypsum bricks with a moisture content of 8.9wt%, soluble P ₂ O ₅ 0.05wt%, pH value = 8.0, SO ₃ : 36.79wt%.

Example 2

Take 95 parts of phosphogypsum, 2 parts of alkali slag, and 3 parts of slag according to the weight ratio, mix _and stir the ingredients evenly, extrude into bricks, and dry naturally at room temperature to obtain the product _. 0.06wt%, pH=8.2, SO ₃ : 37.0wt%.

Example 3

According to the weight ratio, take 91 parts of phosphogypsum, 3 parts of lime, 4 parts of fly ash, and 2 parts of aluminum slag. After the ingredients are mixed and stirred evenly, they are extruded into bricks and dried naturally to obtain modified phosphogypsum bricks. The water content is 8.4wt. %, soluble P ₂ O ₅ 0.04wt%, pH value 7.6, SO ₃ : 36.3wt%.

Example 4

According to the weight ratio, take 93 parts of phosphogypsum, 3 parts of cement, 2 parts of alum, and 2 parts of calcium carbide slag. After the ingredients are mixed and stirred evenly, they are extruded into bricks and dried naturally to obtain modified phosphogypsum bricks. The moisture content in the product is 9.2 wt%, soluble P ₂ O ₅ 0.06 wt%, pH value=8.0, SO ₃ : 37.8 wt%.

Example 5

Take 94 parts of phosphogypsum, 2 parts of white mud, 3 parts of red mud, and 1 part of steel slag according to the weight ratio. After the ingredients are mixed and stirred evenly, they are extruded into bricks and dried naturally to obtain modified phosphogypsum bricks. The water content is 8.5wt%. , soluble P ₂ O ₅ 0.04wt%, pH value 7.4, SO ₃ : 36.92wt%.

Applications

Modified phosphogypsum bricks are mainly used in cement enterprises. Combined with the cement type and the amount of mixed materials, the content of SO ₃ in modified phosphogypsum determines the amount of modified phosphogypsum in cement. It is identified by testing the performance of cement with national standards The performance of modified gypsum bricks. See Table 1 for the weight percentage of modified phosphogypsum in cement ingredients, and see Table 2 for the physical properties of the cement.

Table 1 Cement formula Example number clinker slag limestone Modified Phosphogypsum natural dihydrate gypsum 6 95 5 7 81 8 6 5 8 95 5 9 81 8 6 5

Table 2 Physical properties of cement Example number Clinker Specific surface area (m ₂ /kg) Water demand (%) Coagulation time (h: min) stability 3-day strength (MPa) 28-day strength (MPa) initial setting final set anti-stress Bending resistance anti-stress Bending resistance 6 5.0 355 26.2 1:58 3:08 qualified 31.4 6.4 56.1 8.8 7 4.9 350 27.1 2:03 3:19 qualified 26.9 5.6 54.8 9.4 8 5.0 360 26.7 2:50 4:17 qualified 25.6 5.0 51.0 8.1 9 5..2 350 27.5 2:15 3:50 qualified 23.2 5.4 52.3 8.2

It can be seen from the data in the table that if modified phosphogypsum is used instead of natural gypsum as cement retarder, the compressive strength of cement can be increased by 2-6MPa, and the flexural strength can also be significantly improved.

Claims (3)

1. A modified phosphogypsum brick, which is characterized in that it contains 80-95wt% phosphogypsum, 2-15wt% reinforcing agent, 3-10wt% modifier components, and the sum of each component is 100wt%. , natural drying, wherein the reinforcing agent is any one or more of blast furnace slag, fly ash, steel slag or other industrial waste slag, and the 3-10wt% modifier is 0-10wt% alkali Reactive substances: any one or two of carbide slag, alkali slag, white mud, cement, lime, red mud, and 0-10 wt% of industrial aluminum slag or alunite or calcined bauxite, the modified phosphogypsum brick Water content _< 10wt%, _SO3 >35wt%, pH>7, soluble _P2O5 <0.1wt%. 2. The method for preparing phosphogypsum bricks according to claim 1, characterized in that the ingredients are mixed according to the above-mentioned ratio of ingredients, and then mixed, extruded and naturally dried. 3. The application of the phosphogypsum brick as claimed in claim 1. , which is characterized in that it replaces natural gypsum as a cement retarder, and its added amount is 4-8wt% by weight of cement.