Natural pozzolanic additives (Р)

Natural pozzolanic additives are usually materials of volcanic origin or sedimentary rocks suitable chemical and mineralogical composition. They must meet the general definition of pozzolans. Germany has two kinds of natural pozzolan. It is a volcanic tuff and the Rhine caused by meteorites Bavarian runs (Suevit) Nёrdlingenskom in stock.

Natural volcanic pozzolanic additives (Q) Natural pozzolans is thermally activated materials of volcanic origin, or baked clay, shales or sedimentary rocks. They must meet the general definition of pozzolans.

Ash (V, W) Fly ash is obtained by mechanical or electrostatic deposition of dust particles from the flue gases of combustion plants micronized coal. The ash that is produced by other methods can be used in the production of cement if complies with EN 197-1, others - can not be used.

Fly ash is composed of glassy spherical particles with a diameter of 0.5-100 microns (see Figure 1.26). This latent hydraulic and their composition can be rich in silica and lime. The first of these has pozzolanic properties; the latter may additionally have hydraulic properties.

According to standards EN 196-2 the loss on ignition for 1 hour front fly ash should be no more than 5%. Fly ash with a loss on ignition of 5 to 7% by weight can also be acceptable, provided that certain requirements of strength, in particular to the frost in accordance with applicable standards or regulations for concrete and mortar are made. When used in the composition of cement fly ash with a loss on ignition of from 5% to 7% by weight, the upper limit of 7.0% should be indicated on the packaging and delivery of documents cement.

Natural volcanic pozzolanic additives (Q)

Natural pozzolanic additives are usually materials of volcanic origin or sedimentary rocks suitable chemical and mineralogical composition. They must meet the general definition of pozzolans. Germany has two kinds of natural pozzolan. It is a volcanic tuff and the Rhine caused by meteorites Bavarian runs (Suevit) Nёrdlingenskom in stock.

Natural volcanic pozzolanic additives (Q)

Natural pozzolans is thermally activated materials of volcanic origin, or baked clay, shales or sedimentary rocks. They must meet the general definition of pozzolans.

Ash (V, W)

Fly ash is obtained by electrostatic or mechanical precipitation of dust-like particles from the flue gases of combustion plants micronized coal. The ash that is produced by other methods can be used in the production of cement if complies with EN 197-1, others - can not be used.

Fly ash is composed of glassy spherical particles with a diameter of 0.5-100 microns (see Figure 1.26). This latent hydraulic and their composition can be rich in silica and lime. The first of these has pozzolanic properties; the latter may additionally have hydraulic properties.

According to standards EN 196-2 the loss on ignition for 1 hour front fly ash should be no more than 5%. Fly ash with a loss on ignition of 5 to 7% by weight can also be acceptable, provided that certain requirements of strength, in particular to the frost in accordance with applicable standards or regulations for concrete and mortar are made. When used in the composition of cement fly ash with a loss on ignition of from 5% to 7% by weight, the upper limit of 7.0% should be indicated on the packaging and delivery of documents cement.

Level (8 points)

Fly ash rich in silica (V)

Fly ash is obtained by electrostatic or mechanical precipitation of dust-like particles from the flue gases of combustion plants micronized coal. The ash that is produced by other methods can be used in the production of cement if complies with EN 197-1, others - can not be used.

Fly ash is composed of glassy spherical particles with a diameter of 0.5-100 microns (see Figure 1.26). This latent hydraulic and their composition can be rich in silica and lime. The first of these has pozzolanic properties; the latter may additionally have hydraulic properties.

According to standards EN 196-2 the loss on ignition for 1 hour front fly ash should be no more than 5%. Fly ash with a loss on ignition of 5 to 7% by weight can also be acceptable, provided that certain requirements of strength, in particular to the frost in accordance with applicable standards or regulations for concrete and mortar are made. When used in the composition of cement fly ash with a loss on ignition of from 5% to 7% by weight, the upper limit of 7.0% should be indicated on the packaging and delivery of documents cement.

 

Field of the Invention -This invention relates to a high utilization of fly ash and in particular, the recovery process silica and alumina from fly ash, and more particularly relates to a method, wherein the first silica is recovered from fly ash, keeping Al ratio to Si, greater than or equal to 2, then known method, the metallurgical alumina, the remainder of which is used as a filler or for cement.

BACKGROUND-A large number of fly ash comes from power plants that burn coal, bringing serious pollution and losses to agriculture and natural ecology around the stations. Therefore, this project of high utilization of fly ash is an urgent need to translate.

Fly ash is also a source of minerals. Usually it contains approximately 15-40% Al2O3 and, for the most part, more than 40% SiO2, and fly ash with a high content of Al contains even greater than 40% Al2O3 and approximately 50% SiO2.

Lime ash dust (W)

Fly ash is also known as influenza ash is a residue produced in the combustion, and includes fine particles that rise with the flu gases. The ash, which does not increase, referred to as bottom ash. In the industrial context, fly ash generally refers to the ashes produced during the combustion of coal. Fly ash is generally captured by electrostatic precipitators or other equipment particle filtration before the flue gases reach the chimneys of power plants, coal-fired, and at the bottom ash removed from the furnace base, in this case, together known as coal ash. Depending on the source and coal burned structure, components of fly ash vary considerably, but all fly ash contains a significant amount of silicon dioxide (of SiO) (and amorphous and transparent) and slaked lime (CEO), both being local ingredients in many coal-bearing strata of rock.

In the production of hydraulic binder used slag mixture of different chemical and mineralogical composition with a high content of SiO2, and therefore its properties and applications is usually regarded with lime-pozzolan binder. However, as the artificial mineral additives, a mixture of ash and slag have a number of differences from the pozzolanic additive due to its high content of A12O3, CaO Fe2O3i, in their composition may not had time to burn from the combustion of the fuel and organic carbon. The presence of CaO is higher than 15% may impart ashes and slags obtained from the combustion of coal, the property exhibit hydraulic activity without introducing into it an alkaline curing activator or sulfate. The presence of these products aluminate and calcium aluminosilicate enhances the binding properties of ash and slag.

Similarly lime-slag binder content tszvesti in the lime-ash binder should be in the range of 15-30%; properties of this binder and scope similar to lime-slag binder.

One of the most active hydration is angry ash from the burning of oil shale - Kukersite containing up to 50% of CaO. Further crushing the ash exhibits pronounced cementing properties, and in the production of shale ash-Portland cement with fly ash content of 20-40% can be obtained cement marks 400, 500 and 600.

Calcined shale (T)

Slate is a bituminous, calcareous shales contain an average of 11-20% organic matter. Other major components are calcium carbonate (about 41%), clay minerals (about 27%) and quartz (about 12%). In Germany, the use of oil shale is concentrated mainly in the north-western slope of the Swabian Alps (region Dotternhausen in Baden-Württemberg).Goryuchy slate can serve both as a fossil fuel, as well as the clay component in the clinker burning process. When blowing in a special furnace at a temperature of about 800 ° C in a fluidized bed formed by a binder which has a hydraulic or pozzolanic properties. Formed with the heat of combustion is used to generate electricity. In accordance with the composition of the natural starting material containing combustible phase consists of slate klinkeroobrazuyuschih oxides, mainly silicon dioxide (SiO2), in addition it contains small amounts of free calcium oxide (CaO), calcium sulfate, and larger proportions of pozzolanic oxides. Accordingly, in a finely divided state, burned shale must be expressed hydraulic properties as portland cement and pozzolanic calcined shale svoystva.Soglasno requirements should, when tested in accordance with EN 196-1 achieved after 28 days compressive strength of at least 25.0 MPa. The test solutions can be obtained only with finely ground burnt shale cement instead. Samples after preparation of mortar prisms are up to 48 h., Then removed from the mold and stored until testing (testing) of not less than 90% in relative humidity. Degree of stretching (expanding) the calcined slate when tested in accordance with EN 196-3 using a mixture containing 30% of calcined slate with 70% of cement CEM I in accordance with EN 197-1, should be up to 10 mm

Limestone (L, LL)

Limestone should meet the following requirements:

a) the content of calcium oxide (CaO) calculating the amount of calcium carbonate (CaCO3), the contents of which should be less than 75%;

b) the clay content is determined methylene solution in accordance with EN 933-9 and should not exceed 1.20 g / 100 g To test lime must be ground to a fineness of about 5,000 cm2 / g. Specific surface area is determined in accordance with EN 196-6.

c) the total organic carbon (TOC) for the EN 13639 test methods shall comply with one of the following criteria:

- LL: not exceed the mass fraction of 0.20%;

- L: must not exceed the mass fraction of 0.50%.

 

Izvestnyak- widespread monomineral rock composed of calcite; it can be easily determined by a violent reaction with hydrochloric acid. Due to the wide distribution, ease of handling and chemical properties of limestone is mined and used to a greater extent than other species, second only to the sand and gravel deposits. The limestones are of different colors, including black, but the most common breed of white, gray or have a brownish tint. The bulk density of 2.2-2.7. This soft rock, easy to scratch the knife blade. Limestone effervesce rapidly by reaction with a dilute acid. In accordance with its sedimentary origin has a layered structure. Net Limestone consists of calcite (rarely with a low content of other forms of calcium carbonate - aragonite). Present and impurities. The limestones are found in almost all continents except Australia. They were formed in different geological epochs. Seam Thickness varies from a few centimeters to hundreds of meters. The limestones are common in the United States and take up 75% of the country. In Russia, the limestone common in the central regions of the European part of, as well as common in the Caucasus, the Urals and Siberia. Limestone (in the broadest sense) have an extremely diverse range of applications. They are used in the form of lump limestone, crushed stone, piece (Saw, wall) and quarry stone, facing slabs, mineral crumbs, crushed sand, mineral powder, mineral wool, limestone powder. The main consumers - the cement industry (limestone, chalk, marl), construction (obtaining building lime, concrete, plaster, mortar, masonry walls and foundations; decorative-facing work, etc.), road and rail construction, rock placement for coastal protection and waterworks, metallurgy (limestone and dolomite - fluxes and refractories processing nepheline ore into alumina, cement and soda), agriculture (limestone flour in farming practices and animal husbandry), oil and coke, food (especially sugar), pulp and Paper, glass (limestone, chalk, dolomite), leather (limestone), rubber, cable, paint and varnish industry (chalk as a filler). Other areas of application - polishing products, non-ferrous metals and nacre (limestone), electric welding (chalk to cover the electrodes), writing chalk (chalk), insulation of building structures and technological equipment (mineral wool), etc.

The quartz dust (D)

Quartz dust formed during production of ferrosilicon and silicon, quartz and carbon alloys in an electric arc furnace. It consists of very fine globular particles 0.02-1 microns in diameter containing amorphous silicon dioxide, at least 85%.

Quartz dust must satisfy the following requirements:

a) Loss on ignition (RFP) was measured according to EN 196-2 at 1 hour annealing time, the mass fraction of the SPT must not exceed 4.0%;

b) the specific surface area (BET) of untreated silica dust when tested in accordance with ISO 9277 should be at least 15.0 m2 / g;

For general use grinding clinker and calcium sulfate, silica dust in their original condition, compressed or compressed with addition of water to form granules.

Small components

 

Calcium sulphate

Sulfatkaltsiya (CaSO4) - inorganic compound, the calcium salt of sulfuric acid.

Located in nature in the form of dihydrate CaSO4 • 2H2O (gypsum, selenite) and anhydrous state - anhydrite.

Anhydrous calcium sulfate - colorless crystals under normal conditions - with the rhombic crystal lattice, the density of 2.96 g / cm³, melting point 1450 ° C. At elevated temperatures (above 1200 ° C) can exist in the form of a stable cubic or two metastable modification of α- and β-hexagonal modification. Very slowly adds water, hydrating crystalline to 1/2 or 2 molecules of water to 1 molecule of sulfate, respectively, CaSO4 · 0,5H2O and CaSO4 · 2H2O. Slightly soluble in water. The solubility decreases with increasing temperature, if at 20 ° C, it was 0.2036 g / 100 g of water, the water near boiling point (100 ° C) is reduced to 0.067 g of sodium sulfate per 100 g of water. Dissolved in water, natural calcium sulfate is one of the factors that determine the hardness of water.

The physical properties of the calcium sulfate dihydrate

When the temperature rises, but not more than 180 ° C, calcium sulfate dihydrate loses part of the water turning into a semi-aquatic - the so-called "plaster zhzhёny" fit for further use as a binder. Upon further heating to 220 ° C gypsum loses water to form the anhydrous CaSO4, which during prolonged storage only absorbs moisture and becomes hemihydrate. If firing is conducted at a temperature above 220 ° C, the obtained anhydrous CaSO4, which does not absorb moisture and have not "grasped" by mixing with water (this substance is often referred to as "dead gypsum"). Upon further heating to 900-1200 ° C can be obtained "hydraulic gypsum" which, after cooling properties regains contact with water. The first method partial degidratitsii used in industrial environments to obtain calcium sulfate hemi-hydrate (burnt gypsum, alabaster) CaSO4 ∙ 0,5H2O, heating the dihydrate to about 140 ° C, the reaction equation: CaSO4 · 2H2O = CaSO4 · 0,5H2O + 1,5H2O.

receipt

In industrial scale is produced as a part of natural minerals, such as gypsum, selenite or alabaster, or obtained synthetically - fusing CaCl2 with K2SO4.

In analytical chemistry, it can be obtained by the influence of sulfuric acid as the oxide, hydroxide, carbonate, oxalate or calcium acetate.

Formed by the oxidation of calcium sulfide when heated to 700-800 ° C by reaction of CaS + 2O2 = CaSO4.

Significant volumes of plaster used in construction (it is made from dry plaster, boards and panels for walls, gypsum stone, architectural details, etc.). Products made of gypsum are characterized by relatively low density, fireproof and relatively low thermal conductivity. Property plaster to harden when mixed with water and has been used in medicine, and the arts. "This is the property of gypsum is widely used in orthopedics, traumatology and surgery for the manufacture of plaster bandages which provide a record of individual body parts. Curing kneaded with plaster with water accompanied by a slight increase in volume. This allows for fine reproduction of all details of modeled forms that are widely used by sculptors and architects. "

The cement admixture

According to GOST 24640-81 Additives for cements are divided into 5 classes.

1. The components of the material composition (active mineral supplements).

2. Fillers.

3. Technology - grinding aids.

4. Control the basic properties of the cement:

- Setting time;

- Accelerate the hardening;

- Increasing strength;

- Increase the porosity of the cement - sandstone (air-entraining);

- Regulating the water-holding capacity;

- Increase the plasticity of cement-sand mortar (plasticizers);

- Reduce water wetting the surface of the cement particles.

5. Regulatory special properties of cement:

- Reduce heat;

- Regulatory and dimensional deformation;

- Increase the corrosion resistance;

- Coloring;

- Improving the decorative properties;

- Stabilizing (warning bundle);

- Sealing (bridging the pores)

- Enhancing the heat resistance.