A method for preparing high-strength sulphoaluminate cement with co-production of sulfuric acid by segmental calcination

Abstract

The invention relates to a method for preparing high-strength sulfate aluminum cement co-production sulfuric acid through calcining by steps. The method comprises the following steps: completely replacing limestone and natural gypsum by ardealite, grinding and homogenizing bauxite, slag, silica and anthracite, and preparing the sulfate aluminum cement through calcining by steps. The ardealite utilization rate is greatly improved, and sulfuric acid can be prepared by absorbing high-concentration sulfur dioxide tail gas. The sulphoaluminate cement clinker prepared by the method disclosed by the invention is high in hardening rate, high in early strength and enhanced and stable in long-term strength. The performance test proves that the mechanical strength of the prepared sulfate aluminum cement meets the rapid hardening sulfate aluminum cement standard.

Description

technical field [0001] The invention relates to a method for preparing high-strength sulphoaluminate cement with co-production of sulfuric acid by segmental calcination, which belongs to the technical field of cement preparation. Background technique [0002] With the modernization of engineering technology, the technical requirements for special cement are getting higher and higher. These include the special requirements for the speed of rapid setting and hardening and the hardness of each stage during the construction of special projects, such as the connection construction of cement pipelines, and the construction of foundation sites for large-scale equipment. Although the application and sales market are constantly expanding, they are limited due to the high cost of products, making more users out of reach. On the other hand, as one of the world's three major phosphate fertilizer producers, it is difficult to realize mass utilization due to the restriction of phosphogyp...

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Problems solved by technology

[0003] Chinese patent document CN100351197C discloses a manufacturing process of rapid-hardening sulfoaluminate cement. The raw material proportion of this process is 17-20% of dehydrated phosphogypsum, 45-52% of limestone, and 31-35% of bauxite. The successful use of waste phosphogypsum to replace the natural gypsum in the raw meal mix can partially reduce the cost of sulphoaluminate cement, but the amount of phosphogypsum used in this process only accounts for 17-20% of the raw meal mix, In the invention, 45-52% limestone is needed, which fails to achieve the purpose of effectively utilizing phosphogypsum. In addition, the decomposition of phosphogypsum in the process will release sulfur dioxide, which will cause environmental pollution if not handled properly

[0004] Chinese patent document CN103304170B discloses a method for producing sulphoaluminate cement. Limestone, phosphogypsum, low-grade bauxite and coke are prepared in a certain proportion to make cement raw meal, which is calcined at high temperature after grinding and mixing. In the process, by promoting the decomposition of phosphogypsum as much as possible, the calcium oxide generated by the decomposition replaces part of the limestone, and the sulfur dioxide gas can be collected to prepare sulfuric acid. The ratio of this process is 30-60 parts of limestone, 25-55 parts of phosphogypsum, and low-grade alumina 15-45 parts, this invention can also successfully use waste phosphogypsum to replace natural gypsum, which appropriately reduces the cost of cement, but phosphogypsum has not completely replaced limestone, and there are still as high as 30-60 parts of limestone in the raw material ratio, limestone The carbon dioxide produced by the decomposition will greatly dilute the concentration of sulfur dioxide, which increases the cost and difficulty of sulfuric acid production from sulfur dioxide

By partially converting the phosphogypsum that does not require pretreatment, the mixture that meets the ingredients required for the production of sulphoaluminate cement is obtained, and no additional limestone is required, which expands the application range of phosphogypsum, but this process requires the conversion of phosphogypsum first. Calcium carbonate is then mixed with raw materials and calcined. The required equipment and process are relatively complicated, and the production cost is high.

[0006] After searching, there is no report that completely utilizes phosphogypsum to prepare stable sulphoaluminate cement with fast hardening speed, high early strength and enhanced later strength.

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