BRPI0802967A2 - METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CONSTRUCTION MATERIALS - Google Patents

Abstract

METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS. Refers to compositions and technologies for the manufacture of new materials such as bricks and ceramics for use in construction, based on high asbestos waste. The content of asbestos-containing materials as a main component of starting mixtures may be as high as 80% or more and depends on the properties and percentages of the other components used for preparing these starting mixtures and on the demands on the mechanical properties of manufactured materials. Like other components of developed materials can be used wood burning ash (or oil shale ash, or coal ash, or rice husk burning ash or other grasses, steel slag among others). For the production of concrete-like materials as asbestos tailings binders, lime or steel slag or Portíand cement production tailings can be used, either independently or in combination of these materials. For the production of ceramics it is possible to incorporate natural clay, usually in the range of 10-20%.

Description

METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS

The present invention relates to methods (compositions and technologies), called METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS, based on waste materials containing high asbestos (also called asbestos) or one of six different fibrous minerals from the asbestos group (amozite, chrysotile, crocidolite and the fibrous forms of tremolite, actinolite and antophyllite) that occurs naturally in the environment. Asbestos minerals have long, resilient fibers that can break apart and be flexible enough to be intertwined and also withstand high temperatures. Due to these characteristics, asbestos is used for a wide variety of manufactured products, especially in construction (roofing, bricks and tiles, paper products and asbestos cement products), friction products (car bricks, components). transmission), heat-resistant textile materials and coatings. It is a material with great flexibility and very high tensile, chemical, thermal and electrical resistance.

The asbestos fiber bundles are easily separable from each other and tend to produce very small particulate dust that floats in the air and adheres to clothing. The fibers can be easily inhaled or swallowed and can cause serious health problems.

Because of this, in many countries there are laws prohibiting activities using asbestos or asbestos waste. In accordance with these laws all asbestos products, including asbestos waste, must be buried without reuse. However, these wastes in contact with the environment can contaminate the soil, groundwater, and consequently surface water (rivers, lakes and oceans).

Therefore, in the opinion of the author of this patent, the only solution to the environmental problem of asbestos waste is the development of chemical bonding methods of its fibers in strongly bonded materials to prevent their volatilization in the air. One of the most widespread and widespread. Material from around the world are corrugated Portland cement tiles and similar materials with high asbestos content and very limited service life - 10-15 years.

The objectives of the present patent are:

1. develop a new method of using waste or materials with high asbestos content, chemically bonding their fibers, to use these residues as raw materials in the development of new building materials contributing to the protection of the environment; 2. Develop new materials compositions for application in civil construction with greater economic use, and sufficient characteristic properties in accordance with NBR-8953 and NBR-13279. The results of the research, supported by METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS, focus on this particularity of Portland asbestos cement roofing waste as the primary material for the production of asbestos materials. construction, in particular of concrete-like materials and ceramics.

The content of asbestos-containing materials as a main component of starting mixtures can be as high as 80 - 85%, depending on the properties and percentages of the other components used to prepare these starting mixtures and the demands on the mechanical properties of manufactured materials. The present patent includes two types of new building materials with different starting mix compositions and manufacturing technologies: concrete-like material and ceramics.

The first patented material in METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS are solid bricks, with holes and blocks with properties similar to the properties of concrete.

For the realization of the first patent product (bricks with properties similar to the properties of concrete) at the industrial level can be used as binder the residue of lime production (or market lime, or steel slag of different technological processes), except material containing asbestos. In case of absence of them can also be used Portland cement. In addition, as other components of the starter mixtures, the following environmentally pure and always available materials (without heavy metals above NBR demands) can be used:

• wood burning ash (or oil shale ash, or coal ash, or rice husk burning ash or other grasses and other relatively inexpensive locally available sediment sludge),

• steel slag from different processes;

• natural sand or clay. Silt, gravel, shear and tailings from natural rocks or other aggregate types with partial decrease of sediment mix percentage may be used. Lime production residues are composed of lime with total oxides in non-volatile base (CaO + MgO) <88%, ie with total content of other chemical elements, badly burnt limestone, etc., more than 12% (NBR-6453 ). Lime production residues used in this study have more than 18% CaCCb. However, the CaC03 content may differ and depends on the quality of limestone burning, the time after lime manufacture and the storage conditions. The final destination of this waste has generated major environmental and economic problems.

The technology of manufacturing concrete-like materials from METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS includes the following operations: 1. grinding of asbestos-containing materials to a level of 0.5 mm of grain;

2. dosage of mixing components in desirable percentage, which depends on expected property values of the end products. The content of asbestos-containing material may be as high as 1% to 90% by weight with actual sludge moisture up to 80% or more without preliminary drying;

3. homogenization of mixture of components;

4. exposure of component mixtures for 20-30 minutes for termination of exothermic lime hydration reactions;

5. compaction of homogenized mixture with experimentally determined forming pressure;

6. depositing the compacted materials in open air at ambient temperature or autoclaving under conditions (temperature and pressure determined in advance) in case of use as residual lime binders or virgin lime; deposit of compacted materials in a humid environment (in case of use as binder Portland cement or steel slag).

The homogenized mixture will be compacted by the pressing method with different compaction efforts on one side or (much better) on two sides. Two-sided ready-mix compaction enhances 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 open air cure time.

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

The strength value of this material may be increased by changing the percentage of the components of starter mixtures, especially the marketable lime, commercial lime or Portland cement residue, steel slag, and other binder materials, or with change of technological processes analogous to concrete (increase in the degree of granulometry in the grinding of lime production residues or steel slag, formation pressure, or use of the two-sided material pressing method, etc.). According to NBR 7170 (1983) the uniaxial strength of solid bricks should be as follows: Class A <2.5 MPa;

Class B 2.5 <4.0 MPa;

Class C> 4.0 MPa.

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

The second patented material in METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT FOR PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS are ceramic materials, developed from mixtures of asbestos-containing materials, with contaminated waste with heavy metal content above the demands of Real moisture NBR (up to 80% or more) without preliminary drying and asbestos content up to 80% by weight of initial mixtures.

Technological processes for manufacturing second-rate ceramic materials include the following operations:

• grinding asbestos-containing materials to a level of 0.1 mm of grain;

• Dosing of mixing components (mixing sediment material with ash or other similar components to dry the initial mixture) in a desirable percentage, which depends on expected property values of the end products;

• homogenization of mixture of components;

• compaction of homogenized mixture with experimentally determined formation pressure;

• depositing compressed materials in open air at ambient temperatures for drying to constant weight;

• Burning with pre-chosen temperature and regime.

Asbestos-containing material is mixed with other types of industrial waste that are always available, named above as production components of concrete-like materials and other relatively inexpensive components, incorporating natural clay in case of lack of clay components. For the production of ceramics it is possible to incorporate natural clay, usually in the range of 10 - 20%.

The homogenized mixture must be compacted by the extruder pressing or extrusion method and dried to constant weight. Dry products should be burned at approximately 700 to 950 ° C for up to 6 hours at maximum temperature.

The three-point flexural strength values of the burnt samples range from 3 to 14 MPa. According to NBR 7171 (1992) the uniaxial strength of ceramic blocks must be as follows:

Class 15 = 1.5 <2.5 MPa, Class 25 = 2.5 <4.5 MPa. Experimental results of this patent demonstrate that materials obtained with the method of this patent can replace all Class A, B and C solid bricks and Class 15 and 25 ceramic blocks.

Comparison of strengths of new ceramics with conventional ceramics demonstrates the advantage of ceramics of HIGH ASBESTOS CONTENT METHODS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS. Water absorption capacity (from 9.2 up to 17.8%) also corresponds to the demand for NBR 7171 for ceramic masonry block (it should not be less than 8% or more than 25%).

All ceramic materials developed have heavy metal leaching much lower than the requirements defined in Brazilian and international standards. The low cost of raw materials (asbestos cement tile rejects and industrial waste) ensures a great economic effect for the production of these materials.

Resistance values and other mechanical properties of materials presented in both parts of this patent can be increased by changing the percentage of the starting mix components and by changing technological processes (compaction pressure, temperature and firing time at maximum temperature, heating and cooling, etc.) according to the demands of civil construction or NBR.

The use of these composites of industrial waste above used as raw material for the manufacture of materials similar to the concrete and ceramics of this patent, allows to obtain building materials with characteristics equal to or superior to those of traditional materials (bricks, tiles, etc.). ) presenting, however, but with lower cost price.

In the event of a local lack of lime production waste as the main binder material or to increase the strength of the end product, the lime production waste may be replaced by the following traditional binder materials:

• virgin lime of traditional construction (market lime) without residues of lime production or the mixture between them,

• independent, lime-free, lime-free Portland cement or mixtures of lime,

• High CaO milled steel slag without virgin lime and without lime production residues or the mixture between them.

The technological processes for manufacturing materials of this patent include the following operations:

1. milling asbestos-containing materials to a level of 0.1 mm of grain;

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

3. homogenization of the mixture of components; compaction of the homogenized mixture with experimentally determined formation pressure;

5. depositing the compressed materials in open air at ambient temperature for drying to constant weight;

6. Burning with pre-chosen temperature and regime.

The use of these industrial waste composites allows the construction of building materials with characteristics not inferior to the characteristics of conventional building materials, produced from traditional natural raw materials (natural stones, sand, silt, high plasticity clays, etc) with higher commercial cost binders (Portland cement).

The biggest advantages of METHODS OF USING HIGH ASBESTOS CONTENT AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS compared to traditional methods of producing solid bricks and ceramic blocks are:

1. energetic: for the production of materials similar to the developed concrete, it is not necessary to manufacture high temperatures of solid bricks with the loss of great energy;

2. mechanical strength: the experimental results of this patent include only research results exclusively with asbestos-containing material tailings and lime production residues. Undoubtedly, traditional binder materials (Portland cement and market lime) can significantly increase the strength values of new materials;

3. economical: very low cost of raw materials - industrial waste (asbestos waste material, lime production residues, ash from different fuels, steel slag, etc.) ensuring a high economic effect of producing these materials ;

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

5. Social: Utilization of all 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.

The products obtained by the technologies of HIGH ASBESTOS CONTENT METHODS. AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS they are composed based on the maximum use of non-hazardous industrial class II waste and therefore have a strong contribution to environmental protection issues.

Claims (5)

1. METHODS OF USING HIGH ASBESTOS MATERIALS AS A MAIN COMPONENT OF PRODUCTION OF NEW CIVIL CONSTRUCTION MATERIALS These are various compositions and technologies characterized by being obtained by blends of the following materials: -1. tailings from high asbestos materials, -2. wastes from lime production (or market-based lime, or steel slag from different technological processes, or Portland cement). It is also possible to use as components of new materials-1. wood burning ash (or shale ash, or coal ash, or rice husk or other grass burning ash, or steel slag and other relatively inexpensive locally available sediment water), - 2. For the production of ceramics it is possible to incorporate natural clay, usually in the range of 10 - 20%. Technological processes for manufacturing materials similar to the concrete of this patent include the following operations: -1. milling asbestos-containing materials to a level of 0,1 mm of grain or finer; dosage of mixing components in desirable percentage, which depends on the expected property values of the end products; homogenization of the mixture of components; compaction of the homogenised mixture with experimentally determined formation pressure; depositing the compacted materials in open air at ambient temperature or autoclaving under conditions (pre-determined temperature and pressure) in case of use as residual lime binders or virgin lime; depositing compacted materials in a damp environment (in case of use as binder Portland cement or steel slag). The technological processes for manufacturing ceramic materials of this patent include the following operations: -1. milling asbestos-containing materials to the level of 0.1 mm grains or fines, dosage of mixing components in desirable percentage, which depends on expected property values of the end products; homogenization of the mixture of components, compaction of the homogenized mixture with experimentally determined formation pressure; drying to constant weight, burning of the dried materials at the previously chosen temperature and regime.