RU2756639C1 - Raw mixture and method for preparing active mineral additive to cement - Google Patents

Abstract

FIELD: binders production.

SUBSTANCE: invention relates to the production of binders, can be used to obtain general construction cements. According to the first option, the raw mixture contains an active mineral component - a flask and a gypsum-containing component of a by-product of phosphoric acid production - phosphogypsum, with a hydrated water content of no more than 30% to the total dry matter weight. Contains additionally a carbon-alkali reagent, with the following ratio of components when converted to dry matter, wt.%: flask - 50, phosphogypsum - 33.3, carbon-alkali reagent - 16.7. The method includes grinding the investment ring and phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins, followed by sending the calculated number of components into an autoclave, heat treatment at a temperature of 100-133°С and the content of hydrated water in the mixture no more than 30% of the total dry matter weight, packaging of the finished additive. Then a dry carbon-alkali reagent is introduced and everything is mixed in a mixer. The resulting additive is introduced in an amount up to 20% by weight of the cement. According to the second embodiment, the ratio of the components in terms of dry matter, wt.%: flask - 45-48.3, phosphogypsum - 33.3, building lime - 1.7-5, carbon-alkali reagent - 16.7.

EFFECT: expanding the range of widely available synthesized additives for the production of cement, aimed at reducing electricity consumption when grinding cement and reducing the specific consumption of the main fuel when burning clinker.

4 cl, 2 tbl

Description

The invention relates to the production of binders, can be used to obtain general construction cements.

Known active mineral additive for cement [RU patent for invention No. 2581437, IPC С04В 11/30, С04В 7/52, publ. 04/20/2016, bul. 11], which contains low-calcium ash-and-slag waste from the thermal power plant (active mineral component) with an aluminum oxide content of 17.75% and a gypsum-containing component, which is used as a by-product of phosphoric acid production - phosphogypsum, with a hydrated water content of not more than 30% of the total dry weight substances and the content of components in terms of dry matter, respectively, wt. %: ash and slag waste - 66.7; phosphogypsum - 33.3.

The disadvantage of an active mineral additive for cement is the high dispersion of its main component - ash and slag. This complicates its transportation, storage, dosing, increasing the cost of manufacturing the additive.

As a prototype, a raw mixture was adopted for the preparation of an active mineral additive to cement [RU patent for invention No. 2733360 "Active synthesized additive for cement and a method for its preparation", IPC С04В 22/08, С04В 7/13, С04В 40/00, С04В 111 / 20, publ. 01.10.2020, bul. 28]. The raw mixture contains an active mineral component and a gypsum-containing component of a by-product of the production of phosphoric acid - phosphogypsum, with a hydrated water content of not more than 30% to the total dry matter mass, as well as building lime, and as an active mineral component, a flask with a SiO ₂ content of 70- 90%, Al ₂ O ₃ 7-18% with the following ratio of components when converted to dry matter,. %: investment ring -54-58; building lime - 2-6; phosphogypsum - 40.

The essential features of the invention in terms of the additive (first option) coincide with the following set of prototype features: an active mineral component - a flask with a SiO2 content of 70-90%, Al2O3 7-18% and a gypsum-containing component of a by-product of phosphoric acid production - phosphogypsum, with no hydrated water content. more than 30% to the total dry matter mass.

The essential features of the invention in terms of the additive (second option) coincide with the following set of prototype features: the active mineral component is a flask with a SiO2 content of 70-90%, Al2O3 7-18%, building lime and a gypsum-containing component of a by-product of phosphoric acid production - phosphogypsum, with a content hydrated water no more than 30% of the total dry matter mass.

For the preparation of Portland cement from a known raw mixture, a significant amount of electricity is consumed when grinding cement, and we also observe an increase in the consumption of the main fuel when burning clinker.

Known complex additive for Portland cement [RU patent for invention No. 2431623, IPC С04В 22/00, С04В 24/26, С04В 103/60, publ. 20.10.2011, bul. 29], which describes a method for its preparation, including grinding and mixing on a high-speed mixer, until a homogeneous sludge-like mixture is obtained at the following quantitative ratio, pre-processed, ingredients, wt. %: gypsum or anhydrite 30-54, superplasticizer C-3 0.5-4.5, flue dust 10-25, ash and slag waste with an aluminum oxide content of at least 25 wt. % 16.5-52.5, carbonate rock 12-35.

However, the known method is costly in terms of the production method using a raw material base of multicomponent composition.

The closest in terms of essential features to the claimed and adopted as a prototype in terms of the method is a method for preparing an active mineral additive for cement [RU patent for invention No. 2733360 "Active synthesized additive for cement and a method for its preparation", IPC С04В 22/08, С04В 7 / 13, С04В 40/00, С04В 111/20, publ. 01.10.2020, bul. 28]. A method for preparing an active mineral additive to cement includes grinding the active mineral component and a gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials not exceeding 5.0 mm, accumulating them in separate bins with subsequent sending the calculated amount of components to an autoclave, heat treatment while keeping in a mixture of hydrated water no more than 30% to the total mass of dry matter, packaging of the finished additive. As an active mineral component, a flask is used, in addition, construction lime is placed in a separate bunker, followed by directing its calculated amount into an autoclave. Heat treatment is carried out at a temperature of 170-188 ° C, with the following ratio of components: flask-54-58%, lime - 2-6% phosphogypsum - 40%. The resulting additive is introduced in an amount of 20-45% of the mass of cement when grinding clinker.

The essential features of the invention in terms of the method (first option) coincide with the following set of prototype features: grinding of the active mineral component and the gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins with the subsequent direction of the calculated the number of components in the autoclave, heat treatment with a content of hydrated water in the mixture of no more than 30% to the total mass of dry matter, packaging of the finished additive.

The essential features of the invention in terms of the method (second version) coincide with the following set of prototype features: grinding of the active mineral component, lime of the construction and gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins with the subsequent direction of the calculated amount of components into the autoclave, heat treatment with a content of hydrated water in the mixture of no more than 30% to the total dry matter weight, packaging of the finished additive.

To neutralize acid residues contained in phosphogypsum, it is necessary to dissolve part of the ash and slag in order to convert alkaline oxides into a soluble state. To achieve this, it is necessary to autoclave a mixture of ash and slag and phosphogypsum at relatively high temperatures and pressures and times. Which increases the energy consumption for production.

The invention is aimed at expanding the range of widely available synthesized additives for the production of cement, aimed at reducing electricity consumption when grinding cement and reducing the specific consumption of the main fuel when burning clinker.

This is achieved by two options for solving the problem.

According to a first embodiment, the raw material mixture for the preparation of an active mineral cement admixture contains an active mineral component - a flask containing SiO ₂ 70-90%, Al ₂ O ₃ 7-18% gypsum-containing component and byproduct phosphoric acid production - phosphogypsum, when the content of the hydrate water no more than 30% to the total dry matter mass. The proposed solution contains an additional component of a carbon-alkali reagent, with the following ratio of components in terms of dry matter, wt. %:

flask - 50

phosphogypsum - 33.3

carbon-alkali reagent - 16.7.

The method for preparing an active mineral additive to cement according to the first option includes grinding the active mineral component - flask and a gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins with the following direction of the calculated amount of components in an autoclave, heat treatment with a content of hydrated water in the mixture of no more than 30% to the total mass of dry matter, packaging of the finished additive. In the proposed solution, heat treatment is carried out at a temperature of 100-133 ° C. Additionally, a dry carbon-alkali reagent is introduced and everything is mixed in a mixer. The resulting additive is introduced in an amount up to 20% by weight of the cement.

The raw mixture for the preparation of an active mineral additive to cement according to the second option contains an active mineral component - a flask with a SiO ₂ content of 70-90%, Al ₂ O ₃ 7-18%, building lime and a gypsum-containing component of a by-product of phosphoric acid production - phosphogypsum, with the content of hydrated water is not more than 30% to the total mass of dry matter. The proposed solution contains an additional component - a carbon-alkali reagent, with the following ratio of components when converted to dry matter, wt. %:

flask - 45-48.3

phosphogypsum - 33.3

building lime - 1.7-5

carbon-alkali reagent - 16.7.

The method for preparing an active mineral additive to cement according to the second option includes grinding the active mineral component - flask, lime of the building and gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins with the following direction the calculated amount of components in the autoclave, heat treatment with a content of hydrated water in the mixture of no more than 30% to the total dry matter weight, packaging of the finished additive. In the proposed solution, heat treatment is carried out at a temperature of 100-133 ° C. Additionally, a dry carbon-alkali reagent is introduced and everything is mixed in a mixer. The resulting additive is introduced in an amount up to 20% by weight of the cement.

Characteristics of the materials used:

1. Active mineral component - flask (GOST R 56196-2014 Active mineral additives for cements. General specifications). Opoka is a natural mineral. The required content of active SiO2 can vary 70-90%, Al ₂ O ₃ - 7-18. It should be noted that the higher the content of SiO ₂ , the higher its activity as an active component of the additive in relation to cement. The flask of the Bryansk and Moscow regions was considered as an example.

2. Building lime (GOST 9179-2018. Building lime. Specifications).

3. Phosphogypsum. It is known that phosphogypsum is a by-product of the production of phosphoric acid from apatites and phosphorites by sulfuric acid treatment. The chemical reaction proceeds according to the scheme: Ca ₅ F (PO ₄ ) ₃ + 5H ₂ SO ₄ = 3H ₃ PO ₄ + 5CaSO ₄ + HF. In terms of chemical composition, phosphogypsum is 96-98% composed of calcium sulfate, which, depending on the conditions for the production of phosphoric acid, can be in dihydrate, semi-aqueous or anhydrous modifications. As impurities in phosphogypsum, 1.0-1.5% phosphorus pentoxide (P ₂ O ₅ ), some silica and sesquioxides (and Fe ₂ O ₃ ) can be present. The use of phosphogypsum has found wide application as a mineralizer in the firing of Portland cement raw mixtures and as an additive in cement grinding instead of gypsum stone. However, phosphogypsum, introduced into cement as a setting time regulator, usually contains up to 25% moisture and is contaminated with impurities of phosphoric and hydrofluoric acids, which can reduce the strength of cements, especially in the early stages of hardening.

4. Carbon alkali reagent (UCHR) - TU 5743-001-22256776-2015. Carbon alkali UShchr reagent.

Was prepared two options for the composition of the proposed mixtures for the preparation of an active synthesized additive to cement (table. 1, table. 2).

Example 1 of the first embodiment of the invention is shown in the composition No. 1 presented in table. 1. Raw ingredients: phosphogypsum - a by-product of the production of phosphoric acid and a flask, pre-checked for foreign inclusions and contaminants. Appropriate sorting is carried out. Then it is crushed to a grain size of not more than 5.0 mm.

After that, separately the flask and phosphogypsum are loaded into separate bunkers with a volume of 6 m ³ , the total calculated moisture content of the components is determined, which is 25%. Determine the total calculated acidity of the components, the pH of which is 6.5-7. Then, the calculated amount, in terms of dry matter, respectively, a flask in an amount of 50% and phosphogypsum in an amount of 33.3%, are sent through conveyor belts to an industrial-type autoclave with a working volume of 6 m ³ . The supply of raw materials is controlled by means of weighing sensors. The supply of steam and water is also controlled by volumetric sensors. The total amount of hydrated water in the mixture should not exceed 30%, taking into account the moisture content of the supplied raw materials. That is, add 5% water.

In an autoclave with constant stirring and a temperature of 133 ° C, the mixture is treated for 30 minutes. The resulting finished additive is cooled for 30-60 minutes. Then dry UShchR is added to the additive in an amount of 16.7% and everything is mixed in mixers. Then they are packed in polyethylene bags of 50 kg. The resulting additive is introduced in an amount up to 20% by weight of the cement.

Example 2 of the second embodiment of the invention is shown in the composition No. 1, presented in table.2. Raw ingredients: phosphogypsum - a by-product of the production of phosphoric acid and a flask, pre-checked for foreign inclusions and contaminants. Appropriate sorting is carried out. Then it is crushed to a grain size of not more than 5.0 mm.

After that, separately the flask, lime and phosphogypsum are loaded into three separate bins with a volume of 6 m ³ , the total calculated moisture content of the components is determined, which is 26%. Determine the total calculated acidity of the components, the pH of which is 6.5-7. Then, the calculated amount, in terms of dry matter, respectively, a flask in an amount of 45%, ground lime in an amount of 5% and phosphogypsum in an amount of 33.3%, are sent through conveyor belts to an industrial-type autoclave with a working volume of 6 m ³ . The supply of raw materials is controlled by means of weighing sensors. The supply of steam and water is also controlled by volumetric sensors. The total amount of hydrated water in the mixture should not exceed 30%, taking into account the moisture content of the supplied raw materials. That is, add 4% water.

In an autoclave with constant stirring and a temperature of 100 ° C, the mixture is treated for 30 minutes. The resulting finished additive is cooled for 30-60 minutes. Then dry UShchR is added to the additive in an amount of 16.7% and everything is mixed in mixers. Then they are packed in polyethylene bags of 50 kg. The resulting additive is introduced in an amount up to 20% by weight of the cement.

Example 3 of the second embodiment of the invention is shown in the composition No. 2 presented in table.2. Raw ingredients: phosphogypsum - a by-product of the production of phosphoric acid and flask, pre-checked for foreign inclusions and contaminants. Appropriate sorting is carried out. Then it is crushed to a grain size of not more than 5.0 mm.

After that, separately the flask, lime and phosphogypsum are loaded into three separate bins with a volume of 6 m ³ , the total calculated moisture content of the components is determined, which is 27%. Determine the total calculated acidity of the components, the pH of which is 6.5-7. Then, the calculated amount, in terms of dry matter, respectively, a flask in an amount of 48.3%, ground lime in an amount of 1.7% and phosphogypsum in an amount of 33.3%, are sent through conveyor belts to an industrial-type autoclave with a working volume of 6 m ³ . The supply of raw materials is controlled by means of weighing sensors. The supply of steam and water is also controlled by volumetric sensors. The total amount of hydrated water in the mixture should not exceed 30%, taking into account the moisture content of the supplied raw materials. That is, add 3% water.

In an autoclave with constant stirring and a temperature of 120 ° C, the mixture is treated for 30 minutes. The resulting finished additive is cooled for 30-60 minutes. Then dry UShchR is added to the additive in an amount of 16.7% and everything is mixed in mixers. Then they are packed in polyethylene bags of 50 kg. The resulting additive is introduced in an amount up to 20% by weight of the cement.

In the case when the additive is used as a raw component, then the presence of the UShchR for some sludge reduces the moisture content to 3%, and since the UShchR is organic, an equivalent amount of the main process fuel is replaced during the roasting of such a raw mixture. As a rule, every 1% of the burn-out additive in the raw mix (dry) saves 15 kg / t class. Additionally, reducing the moisture content of the sludge by 1% saves about 1% of the specific fuel consumption or ≈2 kW / t class. At the same time, phosphogypsum is a mineralizer for burning Portland cement clinker, which additionally affects the reduction of fuel consumption. As a rule, the effect of using a mineralizer leads to a fuel saving of 3-5% of the total fuel consumption for firing. The amount of addition to the raw mix is up to 15%. When grinding cement, UShchR plays the role of a grinding intensifier. Electricity consumption can be reduced by about 1-2 kWh / t of cement. UShchR in cement plays the role of a plasticizer. The cement paste becomes more plastic and the amount of water required to obtain a workable cement-sand mixture is reduced. This can lead to an increase in the strength of the concrete mix.

Thus, the claimed additive can be used as an active mineral additive to obtain general cement grades 400 and higher, in all quality indicators meeting the requirements of GOST 10178-85, as well as as a universal composite additive in the production of Portland cement.

Claims (7)

1. Raw material mixture for the preparation of an active mineral additive to cement, containing an active mineral component - a flask with a SiO ₂ content of 70-90%, Al ₂ O ₃ 7-18% and a gypsum-containing component of a by-product of phosphoric acid production - phosphogypsum, with a content of hydrated water not more than 30% to the total mass of dry matter, characterized in that it contains an additional component - a carbon-alkali reagent, with the following ratio of components when converted to dry matter, wt. %: flask 50 phosphogypsum 33.3 carbon alkali reagent 16.7 2. A method of preparing an active mineral additive to cement according to claim 1, including grinding an active mineral component - a flask and a gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins with subsequent direction the calculated amount of components in the autoclave, heat treatment with a content of hydrated water in the mixture of no more than 30% to the total dry matter weight, packaging of the finished additive, characterized in that the heat treatment is carried out at a temperature of 100-133 ° C, then additionally a dry carbon-alkali reagent is introduced and everything is mixed in the mixer, the resulting additive is introduced in an amount of up to 20% by weight of the cement. 3. Raw material mixture for the preparation of an active mineral additive to cement, containing an active mineral component - a flask with a SiO ₂ content of 70-90%, Al ₂ O ₃ 7-18%, building lime and a gypsum-containing component of a by-product of phosphoric acid production - phosphogypsum, with the content of hydrated water is not more than 30% to the total mass of dry matter, characterized in that it contains an additional component - a carbon-alkali reagent, with the following ratio of components when converted to dry matter, wt. %: flask 45-48.3 phosphogypsum 33.3 building lime 1.7-5 carbon alkali reagent 16.7 4. A method of preparing an active mineral additive to cement according to claim 3, including grinding the active mineral component - flask, lime of the building and gypsum-containing component - phosphogypsum to obtain a homogeneous mixture with a grain size of raw materials no more than 5.0 mm, their accumulation in separate bins with the subsequent direction of the calculated amount of components into the autoclave, heat treatment with a content of hydrated water in the mixture of not more than 30% of the total dry matter weight, packaging of the finished additive, characterized in that the heat treatment is carried out at a temperature of 100-133 ° C, then a dry carbon-alkali reagent is additionally introduced and everything is mixed in a mixer, the resulting additive is introduced in an amount up to 20% by weight of the cement.