Drift bead is a kind of fly ash hollow ball that can float on the water surface. It is gray white, thin and hollow, very light, with a unit weight of 720kg/m3 (heavy), 418.8kg/m3 (light), a particle size of about 0.1mm, and a closed and smooth surface,Thermal conductivitySmall,Fire resistance≥ 1610 ℃, excellent thermal insulation refractory, widely usedLight castableProduction and oil drilling.The chemical composition of floating beadssilicon dioxideandAluminium trioxideIt is characterized by fine particles, hollow, light weight, high strength, wear resistance, high temperature resistance, thermal insulation, insulation and flame retardancy. It is one of the raw materials widely used in the fire resistance industry.
Chinese name
Floating bead
Type
Thermal insulation, fire prevention and high temperature resistance
Application
It is widely used as one of the raw materials in the refractory industry.
Nature
Grayish white, thin and hollow wall, light weight
Features
Fine particles, hollow, light weight, high strength, wear resistance, high temperature resistance, thermal insulation, insulation and flame retardant
Examples of chemical composition of floating beads:
component
SiO₂
Al2O3
Fe2O3
SO3
CaO
MgO
K2O
Na2O
Content (%)
56-62
33-38
2-4
0.1-0.2
0.2-0.4
0.8-1.2
0.5-1.1
0.3-0.9
Physical shape of floating bead
Floating beads under microscope
The picture below shows a floating bead with a hollow structure under the microscope. On the right is a hair. It can be seen that most of the floating beads are smaller than the diameter of a hair.Drifting bead due to coal quality, boiler type, boiler parametersCoal millThe shape of floating beads is different due to different forms, and the size difference of floating beads is more than ten times.
Formation of floating beads
Announce
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The formation mechanism of floating beads: Coal fired power plants often grind coal into pulverized coal and spray it into the furnace of power generation boilers toSuspended combustion。Most of the combustible components (carbon and organic matter) of coal burn, while the non combustible components (silicon, aluminum, iron, magnesium, etc.) of clay begin to melt under the high temperature of 1300 ℃ in the furnace, formingquartz glassAnd mullite.
Source of fly ash floating beads
Fly ash floating bead refers to the fly ash with medium density less than waterHollow glass bead, one of the bead shaped particles of fly ash, is named for its ability to float on water.When the pulverized coal is burned in the boiler of the thermal power plant, the clay material melts into micro droplets, spins at high speed under the action of the turbulent hot air in the furnace, and forms a round silicon aluminum sphere.Gases such as nitrogen, hydrogen and carbon dioxide generated by combustion and pyrolysis reactions rapidly expand in the molten high-temperature silicon aluminum spheres, form hollow glass bubbles under the effect of surface tension, and then enter the flue for rapid cooling. After hardening, they become high vacuum glassy hollow beads, namely fly ash floating beads.Fly ash floating beads are derived from fly ash and have many properties of fly ash, but because of its unique formation conditions, it has superior performance than fly ash. It is a new type of lightweight non-metallic multifunctional powder material, known as the material of the space age.The samples of floating beads used in this paper are from Hebei Xingtai Xuou Floating Beads Factory.
Purpose
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Excellent performance and use of floating beads
highFire resistance。The main chemical composition of floating beads is silicon and aluminum oxides, of whichsilicon dioxideAbout 50-65%,Aluminium trioxideAbout 25-35%.Because the melting point of silicon dioxide is 1725 ℃, and that of aluminum oxide is 2050 ℃, both are high refractory materials.Therefore, the floating beads have extremely high fire resistance, generally up to 1600-1700 ℃, making them excellent high-performance refractories.Light weight, thermal insulation.The wall of the floating bead is thin and hollow, and the cavity is semi vacuum. There is only a tiny amount of gas (N2, H2, CO2, etc.), and the heat conduction is extremely slow.Therefore, the floating beads are not only light in weight (250-450kg/m3), but also excellent in thermal insulation（thermal conductivityRoom temperature 0.08 － 0.1insulation material The foundation has been laid for showing great skills in the field.High hardness and strength.Because the floating bead is of silicon aluminum oxide mineral phase（quartzandMullite）The formed hard glass body has a hardness of Mohs 6-7 and a static pressure strength of 70-140MPa,True density2.10-2.20g/cm3, equivalent to rock.Therefore, the floating beads have high strength.General lightweight porous or hollow materials such asperlite, boiling rock, diatomiteSea pumice、Expanded vermiculiteAll of them are of poor hardness and strength. The thermal insulation products or light refractory products made of them have the disadvantage of poor strength.Their weakness is precisely the strength of the floating beads, so the floating beads have more competitive advantages and wider uses.Fine particle size,Specific surface areaLarge.The natural particle size of floating beads is 1-250 μ m.The specific surface area is 300-360cm2/g, similar to that of cement.Therefore, floating beads can be directly used without grinding.The fineness can meet the needs of various products. Other products are lightThermal insulation materialGenerally, the particle size is very large (such asperliteIf it is grinded, the capacity will be greatly increased and the thermal insulation will be greatly reduced.In this respect, floating beads have advantages.Electrical insulationExcellent.SelectMagnetic beadsThe rear floating bead is an insulating material with excellent performance and does not conduct electricity.Generally, the resistance of insulators decreases with the increase of temperature, while the resistance of floating beads increases with the increase of temperature.This advantage is not possessed by other insulating materials.Therefore, it can be used to make insulating products under high temperature conditions.
Specifications
Specification of floating bead: 60-200m
Applied to coatings and paints
Drift beads have the following advantages when applied to coatings and paints:
1. Low resin consumption/great potential: because in any shape, the sphere has the smallestSpecific surface areaThe floating beads also have the least demand for resin.The accumulation of particles has also been improved.BroadParticle size distributionThe small microspheres can be filled into the gaps between the large microspheres.The result... in fact: high dosage, highSolid content, lowerVOCAnd reduce the dosage of other ingredients;
2. Low viscosity/improved fluidity: unlike irregular shaped particles, floating beads are easy to roll between each other.This makes the system using floating beads have lower viscosity and better fluidity.Moreover, the system canspraySex has also been improved;
3. Hardness/Abrasion resistanceDrift bead is a kind of high strength and hard microsphere, which can enhance the hardness, scrub resistance and abrasion resistance of the coating;
4. Excellent heat insulation effect: due to the hollow spherical structure of floating beads, it has excellent heat insulation effect when filled in the paint;
5. Gloss control: as a kind of filler, floating beads can reduce the gloss and control the surge. Even in the case of high dosage requirements, they can also eliminate commonMatting agentIt is easy to cause a large increase in viscosity, and the cost is low;
7. Opacity: the hollow sphericity of the floating bead makes the light slowly radiate and scatter, and as a result, the coatingCovering power；
eightDispersity: Float beads are dispersed as mineral filler, due to the thick wall and highcompressive strengthIt can withstand all kinds ofblender、an extruderAnd the processing process of the molding machine;
9. NoneCrystalline siliconPollution: Different from other fillers, the content of crystalline silicon in floating beads is below the harmless level.Such floating beads are not regarded as carcinogens, and do not need special hazard warning signs.
10. High solidsIndustrial coatings: Low viscosity, high dosage, reduce VOC, improve hardness, control gloss, increase wear resistancespraySex, reduce cost;
11. Water soluble industrial finish: increase solid content, reduce film permeability, improve corrosion resistance, hardness, inertia, wear resistance, control gloss and reduce cost;
12 Thermal insulationFire retardant coating: High temperature resistance, flame retardant, excellent heat insulation effect;
13 Maintenance coating:Chemical resistanceAnd corrosion resistance, durability, abrasion resistance, low coating permeability, high addition amount and low cost;
fourteenpowder coating : Improve fluidity, hardness, wear resistance, control gloss and reduce cost;
1. Fire resistanceThermal insulation material；Such as light sinteringrefractory bricks, light unfired refractory brick, cast insulation riser, pipe insulation shell, fire protectionThermal insulation coating, thermal insulation paste, composite thermal insulation dry powder, lightweight thermal insulation and wear resistanceFRP、
2. Building materials;Architectural decoration, advanced pavement materials, roof waterproof and thermal insulation coating, road worksModified asphaltetc.
3. Petroleum industry;Oilfield cementing, pipeline anti-corrosion and insulation, subsea oilfield, floating device, oil well drilling mud reducer, oil and gas transmission pipeline, etc.
4. Insulation materials;Plastic activation filler, high-temperature and high-pressure insulator, etc,
6. Space and space development;Composite materials on the surface of satellites, rockets, spacecraft, satellite fire protection layer, marine equipment, ships, deep-sea submarines, etc;
10、powder metallurgy: Made by mixing aluminum, magnesium and other light metalsFoam metal, like thiscompound materialCompared with the base alloy, it has low density, high specific strength and high stiffnessdampingPerformance and wear resistance.[1]
