BRPI0903142A2 - the methods of using phosphate plaster to manufacture building materials - Google Patents

Abstract

THE METHODS OF USING PHOSPHO-PLASTER FOR THE MANUFACTURE OF CIVIL CONSTRUCTION MATERIALS. Refer to the methods (compositions and technology) for application in civil construction, based on phospho-gypsum with a high humidity value (up to 60% or more) without preliminary drying. The phosphor-gypsum content as a main component of initial mixtures can reach the level of 80% or more. As other components of patent materials, the following materials were used: 1. Binder materials: residues from the production of market lime or lime, plaster, steel slag, Portland cement or other locally available materials with binding properties; 2. Drying materials: to avoid the expense of drying the wet phospho-gypsum component, such as vegetable ash, charcoal ash, mineral ash, shale ash, milled steel slag, sand (natural or foundry), dry silts or other relatively inexpensive and locally available water absorbers. In this patent, three different methods (compositions and technologies) were developed for the use of phospho-gypsum as the main raw material in the production of civil construction materials: 1. using mixing press methods; 2. through compaction in vibrating-press or press; 3. through the production of mortars or decorative materials without pressing, without vibrating-pressing and without compaction.

Description

METHODS OF USING PHOSPHO-PLASTER FOR MANUFACTURING CIVIL CONSTRUCTION MATERIALS.

The present invention relates to the methods (compositions and technologies) of using phosphate plaster sludge from the manufacture of phosphate for the production of phosphoric fertilizers. In this process of 1 ton apatite and 1.35 tons of sulfuric acid are forming 1.6 tons of depleted plaster in industrial landfills with moisture value between 30 -60%. The tailings contain fluorine, phosphorus, strontium, silicon, etc., which contaminate air, soils, surface and groundwater.

There are washing and neutralization technologies for this sludge, but their economic efficiency is quite low. A small percentage (due to sulfur and phosphorus altoteor ratio) of phosphate plaster is being used for Portland decking production. The method of using phosphate plaster for soil improvement is also well known, but in very limited quantities (maximum 15 tons per hectare and only once for 5 - 6 years). Sualogistics does not allow to expand the area of use of the waste in the largest distances. That is why millions of tons of phosphate plaster accumulate in the apatite-producing regions, and there is a widespread and recurring need to develop new materials with the highest possible content of this waste to solve environmental problems.

The objectives of the present patent are:

1. develop new compositions of phosphate-plaster construction materials as the main raw material (up to 85% or more) in combination with other local industrial wastes or market materials to make them sufficiently characteristic construction materials according to NBR;

2. develop new technologies for the use of these materials for application in civil construction with greater economic effect and contribute to environmental protection in accordance with NBR standards.

Based on this patent, different civil construction materials can be produced, such as blocks, solid bricks, hole bricks, flagstones, sleepers, ornamental (decorative) materials, etc.

As other components of patent materials the following materials were used: 1. Binder materials: Residues of lime production, or market-based lime, or gypsum, or steel slag, or Potrland cement1 or other locally available materials with binder properties. Waste from lime production is composed of lime with total oxides in the non-volatile base (CaO + MgO) <88%, ie with total content of other chemical elements such as badly burnt limestone, etc., more than 12% (NBR- 6453). Waste from lime production used in this study has more than 18% of CaC03.

However, the CaCO3 content may differ and depends on the quality of limestone burning, the time after lime manufacture and the conditions of its storage. The final destination of this waste has generated great environmental and economic problems;

2. Materials - dryers to avoid drying dumps of wet components considering their moisture during component percent calculations of the initial mix. In this research were used as drying materials such as vegetable ash (wood, or rice husk burning ash or other grasses). It is also possible to use as material dryers charcoal ash, coal ash, oil shale ash, milled steel slag, sand (natural or smelting) or dry silt and other relatively inexpensive and locally available water absorbers. Amounts of clay or wood sawdust may be used, but these decrease the mechanical properties of the end products or increase binder consumption.

In this patent, three different methods (compositions and technologies) of using phosphate plaster as main raw materials for the production of building materials were developed:

1. The production of solid bricks and holes with bricks by means of depressed methods of blending rejected phosphate plaster with the above-mentioned binder materials or other locally available materials with binder properties. The components (phosphate plaster, binders and if necessary osmaterials - dryers) need to be mixed, homogenized and hydrated in different proportions in advance chosen to meet the demands of end product characteristics. Compaction of hydrated mixtures can be performed with one or (better) two-sided presses. Curing bricks with lime or calvirgin residue or plaster may occur in the open air (environment); The production of blocks and bricks by vibration-press compaction or phosphate-plaster blending with Portland cement, slag or mixtures of these in different percentages chosen, homogenized and hydrated with subsequent curing in wet chambers or with coverings of synthetic materials for conservation. as long as possible, or in an autoclave.

3. The production of mortars or decorative materials without pressing, without vibration-pressing and without composting the phosphate-plaster mix with lime-producing waste, with market-dried lime, with plaster or with mixtures thereof in different proportions to achieve the desired mechanical properties and economically pleasing.

Phospho-gypsum contents as a major component of initial mixtures can reach a level of 85% or more, depending on tailings moisture, Binder properties used, compaction methods, water / solids mixtures, curing conditions and mechanical properties requirements. of manufactured materials.

The property values of the materials of this patent, with Portland cement as binder, are roughly equal to the properties of concrete. Materials using lime or virgin lime production residues have the mechanical properties similar to the properties of concrete, but have a long curab time (from six months to one year) when compared to concrete dryness.

Technological processes for manufacturing materials similar to the embodiment of this patent include the following operations:

1. Dosage of mixing components in desirable percentage, which depends on the expected property values of the end products;

2. Hydration or, on the contrary, introduction of materials - dryers, depends on humidity of main raw material;

3. Mixture homogenization of components;

4. Compaction of homogenized mixture with experimentally determined formation pressure;

5. Deposit of compacted materials in the open air at ambient temperature or autoclaving (temperature, pressure and duration) determined in advance for use as residual lime binders or market virgin lime; deposit of the compacted materials in the humid environment (in case of use as a Portland cement or steel slag).

The homogenized mixture will be compacted by the pressing method with different compaction forces on one side or (much better) on two sides. Ready-mix mixing on both sides increases the mechanical properties of the end product. The compaction force in this study was 10 MPa with traditional uniaxial pressure on one side. Mechanical property values increase with cure time in the open air.

The uniaxial compressive strength of samples of different compositions from this study on the 3rd day of cure usually ranges from 2 to 6 MPA1 on the 14th day -4-10 MPa and on the 28th day between 6-15 MPa. Resistance continues to increase up to a year or more.

The strength values of this material may be increased by changing the percentage of the components of initial mixtures, especially the residue content of lime, commercial lime or portland cement, steel slag, other binder materials, by changing technological processes (increasing the degree of fineness in grinding waste from lime production or steel slag, forming pressure, or the use of two-sided material pressing method, etc.), analogous to concrete.

According to NBR 7170 (1983) the uniaxial strength of solid bricks should be as follows: Class A <2.5 MPa;

CIasseB 2.5 <4.0MPa; Class C> 4.0 MPa.

The materials have high values of water resistance and low coefficient of dedication.

Technological processes for the manufacture of the second patented material in Phospho-Plaster Usage Methods for Civil Construction Material are the blocks and bricks through vibration or press decompression developed from mixtures of phospho-plaster with other components, which include the following operations:

1. Dosage of mixing components in desirable percentage, which depends on main tailings moisture, properties of other available components and expected property values of final products; Hydration or, on the contrary, introduction of additives - dryers, depending on the moisture of the main raw material;

3. Mixture homogenization of components;

4. Compaction of homogenized mixture with vibration-press or single-sided or double-sided press for experimentally determined time;

5. Healing in the open air or in damp chambers, or with synthetic material coverings for moisture conservation as long as possible, or in a autoclave, depending on the starting mix compositions and end product demands.

Mechanical property values increase with curing time, but they always stay within or far outweigh NBR demands.

The technological processes of production of the third material of this patent - mortars or decorative materials - have the same first three operations (dosing, hydration and homogenization) with mixtures of lime production residues, market-lime, plaster or mixtures of these in different proportions. to achieve desirable and economically pleasing mechanical properties. The biggest difference is absence of compression or vibration-pressing or other types of compaction. The final product cure takes place in the open air.

The main differences of this patent in relation to other methods are:

1. The use only of phosphate plaster tailings, obtained in extraction processes and preparation of apatite deposits;

2. Utilization of phosphate plaster with moisture from landfills (with water content up to 60% or more) without preliminary drying and without burning (without pollution by sulfur, phosphorus and other elements);

3. Curing of materials takes place without autoclaving, with free air temperature and humidity. But it is also possible to use an autoclave to increase the speed of material strengthening;

4. End product manufacturing technology includes uniaxial one- or (better) two-sided compression. It is also possible to use vibro - press or other compression methods;

5. The only materials used in this research were lime production residues or (in case of lack of residual lime) market lime or plaster cast. But it is also possible to use Potrland cement or other locally available materials with binder properties. The use of Portland decay increases mechanical property values, but also significantly increases the cost price of materials.

The major advantages of the materials of this patent compared to traditional methods of producing building materials are:

1. Energetic: For the production of developed materials not required, high manufacturing temperatures of solid bricks through conventional methods with the loss of high energy;

2. Economical: a very low cost of raw materials - phosphate plaster and industrial waste used in this research - ensuring a high economic effect of production of these materials;

4. Environmental: The method developed in this patent is based on the maximum use of various industrial wastes and therefore has a strong contribution to environmental protection issues;

5. Social: Utilization of all phosphate plaster industrial landfill waste as components of new materials can undoubtedly improve the quality of life of the local population. In addition, for the production of new developed materials it is necessary to create a network of new companies with generation of new jobs.

Claims (1)

1. METHODS OF USING PHOSPHO-PLASTER FOR MANUFACTURING CIVIL CONSTRUCTION MATERIALS include three types of new civil construction materials characterized by being obtained from the following materials: - phosphate plaster sludge in admixture with one of the binder materials or a combination such as: - wastes from the production of lime, - or virgin market lime, - or virgin market plaster, - or steel slag, - or Portland cement1 - or other locally available materials with binder properties, and with one of the materials excess phosphate plaster sludge water dryers such as: - vegetable ash, - or charcoal ash, - or coal ash, - or oil shale ash, - or ground steel slag, - or sand ( natural or foundry), - dry silos or other relatively inexpensive and locally available water absorbers;