Raw Mix for the Production of Portland Cement Clinker

The invention relates to raw mixes for the production of portland cement clinker.

Such clinker is widely used in the manufacture of highgrade cements.

Basic starting materials for the production of portland cement clinker include lime and clay components, and various adjusting additives.

The additives are used as means for adjusting the properties of the raw mix, clinker and cement.

The knowledge of the mechanism of additives and their influence on the mechanical properties of clinker enables a diversification of properties of raw mixes and production of clinker exhibiting a complex of predetermined useful properties.

Thus, it is known to use such modifying additives as CaCl.sub.2, TiO.sub.2 and the like. These additives improve certain properties of a raw mix, such as plasticity and strength performance of clinker. They are, however, in a short supply and expensive. From the economical viewpoint, it is expedient to use production wastes as additives.

Known in the art is a raw mix for the production of portland cement clinker, containing lime and clay components. The composition of this mix also includes an iron-containing component (cinder)--waste from chemical production, and a manganese concentrate for an adjustment of alumina and siliceous indexes. As modifying additives for such mixes, the use is made of e.g. blast-furnace dust which is the waste of blast-furnace metal production, waste of soda production containing up to 70% of CaCl.sub.2.

These raw mixes are widely used. These mixes are used for the production of high-grade clinker. The introduction of additives improves the degree of mineralization, and intensifies the roasting process.

No one additives used can, however, impart to the raw mix and resultant clinker a complex of useful properties.

Known in the art is a raw mix for the production of portland cement clinker containing carbonate, clay and iron-containing components, and oxygen-containing chlorine compounds as a modifying additive with the following proportioning of the components (% by weight):

As oxygen-containing chlorine compounds, use is made of oxidizers: calcium chlorine, hypochlorite, and chlorate.

This raw mix exhibits a complex of useful properties and, moreover, the use of the above-mentioned additives enables a lowering of the roasting temperature in the process of the clinker production. The additive used cannot, however, ensure desired fluidity of a mix, required moisture content and adequate degree of decarbonization.

Clinker produced from this mix exhibits low strength.

It is an object of the invention to provide a raw mix which exhibits valuable properties; such as improved fluidity with minimum required moisture content, as well as an improved degree of mineralization.

In accordance with this and other objects, the invention resides in a mix containing a lime component, a clay component, an iron-containing component, and a modifying additive. According to the invention, the modifying component comprises hydrolysis and yeast production waste liquors and products of neutralization of chlorine-containing off-gas of titanium-magnesium production, with the following proportion of the components (% by weight):

As the lime component, use may be made of, e.g. limestone, chalk, marl. As the clay component use may be made of various clays and loams. As the iron-containing component use may be made of pyrite cinder, ore dust.

As mentioned above, the modifying additive is made of hydrolysis and yeast production waste liquors and products of neutralization of chlorine-containing off-gas from titanium-magnesium production.

Hydrolysis and yeast production waste liquors are the wastes of yeast production plants, and have the following chemical composition (% by weight):

Products of neutralization of chlorine-containing off-gas of titanium-magnesium production comprise a 60-80% solution having the following chemical composition (% by weight):

Content of chlorine up to 15-17% in the products of neutralization of chlorine-containing off-gas from titanium-magnesium production improves the degree of decarbonization of the raw mix at the stage of preparation of coarse sludge by 15-20%.

The presence of chlorine contributes also to the decomposition of organic compounds of hydrolysis and yeast production waste liquors. As a result, the fluidity of the mix increases by 3-5%. Moreover, owing to the presence of chlorine, calcium chloride is formed to intensify the roasting process.

The presence of other components in the products of neutralization of chlorine-containing off-gas has a positive effect on the properties of both raw mix and clinker. Thus Al.sub.2 O.sub.3 contributes to the improvement of reactivity of the mix as it is present in the form of a free oxide. This results in improved strength characteristics of clinker.

The raw mix for the production of portland cement clinker according to the invention exhibits improved physicochemical and mechanical properties. Thus the fluidity of the mix is from 50 to 60 mm which is 3 to 5 mm better compared to the raw mix containing oxygen-containing chlorine compounds as an additive; the degree of decarbonization is also considerably improved (up to 12-18%).

Clinker produced from the raw mix according to the invention has an improved strength from 550 to 560 kgf/cm.sup.2, the roasting temperature is lowered by 80.degree.-140.degree. C., the kiln output is improved by 2-3% and fuel consumption is reduced by 3-4%.

The process for the preparation of a raw mix for the production of portland cement clinker is carried out as follows.

A lime component is preliminarily crushed in two stages: first, in a jaw breaker and than in a hammer mill. Then the comminuted lime component and a clay component are charged in a pre-set ratio into a rod mill, into which is also fed hydrolysis and yeast production waste liquors and products of neutralization of chlorine-containing off-gas of titanium and magnesium production. The resultant comminuted sludge is fed from the rod mill into a coarse sludge basin. The sludge is analyzed to determine the content of CaCO.sub.3, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3, SiO.sub.2 and Cl. The sludge is pumped from the basin into a ball mill, into which is also fed an iron-containing component. They are finely ground together.

For better understanding of the invention, specific examples are given below.

A raw mix for the production of portland cement clinker of the following composition (% by weight) was prepared:

Limestone was first comminuted in a jaw breaker and then, in a hammer mill. Clay and comminuted limestone were charged into a rod mill, to which were also fed hydrolysis and yeast production waste liquors and products of neutralization of chlorine-containing off-gas from titanium and magnesium production. The resultant comminuted sludge was fed to a coarse sludge basin and therefrom, to fine grinding ball mills to be comminuted together with ore dust to a pre-set fineness.

The resultant raw mix had the following properties:

In the production of clinker from this mix, the temperature at which the clinker formation process was completed was lowered from 1500.degree. C. to 1420.degree. C. The strength of clinker produced using this raw mix was 550 kgf/cm.sup.2.

A raw mix for the production of portland cement clinker of the following composition (% by weight) was prepared:

The mix was prepared as described in Example 1.

In the production of clinker using this raw mix, the temperature at which the clinker formation process was completed was lowered from 1500.degree. C. to 1390.degree. C., the strength of clinker produced from this raw mix was 555 kgf/cm.sup.2.

A raw mix for the production of portland cement clinker having the following composition (% by weight) was prepared:

The mix was prepared as described in Example 1. The resultant raw mix had the following properties:

In the production of clinker using this raw mix, the temperature at which the clinker formation process was completed was lowered from 1500.degree. C. to 1360.degree. C., the strength of clinker produced from this raw mix was 565 kgf/cm.sup.2.