Method for preparing high-performance cementing material through negative-pressure anaerobic thermal cracking of phosphogypsum

Abstract

The invention discloses a method for preparing a high-performance cementing material by negative-pressure anaerobic thermal cracking of ardealite, which comprises the following steps: adding water into ardealite, fully stirring to obtain slurry, placing the slurry in a nitrogen environment, and heating the slurry to 50-60 DEG C under the pressure of 0.04-0.06 MPa; the reaction container is rotated at the speed of 30-50 r / min, the temperature of the slurry is maintained at 200-300 DEG C, and the reaction is performed for 60-120 min; and drying and collecting the materials in the reaction container to obtain the gypsum-based cementing material. The material cracking and heating are uniform, the gypsum phase composition is simple, the removal effect on impurities in phosphogypsum is stable, free phosphoric acid and other impurities which have great influence on the performance are removed through over-cracking, and repeated tests prove that the prepared gypsum cementing material is simple in gypsum phase, good in removal effect on organic matter, free phosphoric acid and the like in the material and good in comprehensive performance. The mechanical property is stable.

Description

technical field [0001] The invention relates to a method for preparing a gypsum-based cementitious material by anoxic thermal cracking of phosphogypsum under a negative pressure environment, and belongs to the technical field of inorganic non-metallic materials. Background technique [0002] The traditional process uses phosphogypsum to prepare building gypsum cementitious materials, most of which need to be calcined at high temperature above 600 °C, dehydrate the phosphogypsum from the calcium sulfate dihydrate state, and then undergo aging and other treatments to obtain gypsum-based cementitious materials. For example, in the commonly used high-temperature calcination process, rapid dehydration is carried out at a high temperature of not lower than 800°C in the calciner. Or use a rotary kiln to calcine phosphogypsum at a temperature of 400-600°C, and then prepare the gypsum-based cementitious material by means of aging. These methods have the following problems: (1) Direc...

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Problems solved by technology

These methods have the following problems: (1) direct calcination without pretreatment, incomplete removal of impurities, resulting in large fluctuations in the performance of calcined products, and pretreatment will greatly increase production costs; (2) high calcination temperature and high energy consumption; (3) Subsequent treatment such as aging is required, and the production cycle is long; (4) Calcination is uneven, resulting in over-burning or less, which affects the performance of the powder

Its 2-hour average flexural strength is only 1.2MPa; the traditional calcination method, the temperature is between 600°C and 800°C, and the calcination time is about 3h. After the calcination is completed, it needs to be aged under strict control of humidity and temperature. , its material properties can be improved to a certain extent, but its energy consumption and production cost are greatly increased, and the complex phase composition is difficult to homogenize even after aging treatment, and there are still unstable physical and mechanical properties.

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