Ultra low-alkali portland cement and production method thereof

Abstract

The invention relates to a production method of ultra low-alkali portland cement, characterized by strictly selecting crude fuel with low alkali content and using a scientific clinker formula, wherein, the scientific clinker formula comprises that: the lime saturation factor (LSF) is 95+ / - 1.5, the silica modulus (SM) is 2.20 + / -0.1, the aluminium modulus (AM) is 0.80+ / -0.1, so that the optimal proportioning principle of raw material consisting of 80.3 wt% of high calcium limestone, 12.5 wt% of high silicon sandstone, and 7.2 wt% of converter slag is calculated. According to the invention, the silicate cement clinker produced by using a wet-grinding dry-sintering semidry method has the f-CaO of no larger than 1.0 %, and the litre weight of no less than 1100 g / l; an optimal formula of cement material comprising a ratio of ultra low-alkali portland clinker to ferroalloy slag to high calcium limestone of 70-90 to 7-13 to 4-8 to 2-7 is used to produce 425# ultra low-alkali portland cement, wherein, the alkali content is no larger than 0.4 %, the average alkali content is 0.37 %, so that the international standards of low alkali cement are satisfied.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to an ultra-low-alkali Portland cement and a production method thereof. Background technique [0002] Cement contains alkali, a harmful substance. If the alkali exceeds the standard when mixing concrete, a very harmful alkali-aggregate reaction (AAR) will occur, which will eventually lead to cracking and damage to the concrete from the inside to the outside, which is the key to destroying concrete buildings. an important factor. Alkali-aggregate reaction (AAR) has become a global problem in concrete engineering because of its great harm to the durability of concrete. Harmful alkalis in concrete are not only brought in by cement. Concrete aggregates (sand), water, and admixtures may all bring in harmful alkalis. For example, sand and gravel in Guizhou Province are rich in harmful alkalis and active ingredients. In order to prevent concrete alkali-aggregate re...

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Problems solved by technology

[0004] Document CN00119388 adopts the wet kiln to produce clinker. Although the clinker produced by the wet kiln is of high quality and good strength, due to the high heat consumption (the clinker heat consumption is usually 5234-6490 kJ / kg), Energy consumption is large, and water consumption is large during production, which consumes water resources. my country has listed wet-process cement production as a restricted and eliminated kiln type.

At present, the new dry-process rotary kiln emerging in China is energy-saving (clinker consumption is 3140-3768 kJ / kg), high output and high productivity, but few of them can produce low-alkali cement meeting international standards.

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