Refractories industry accessing standards makes new progress

According to media reports, commissioned by the Ministry of Industry, China Association recently held refractories refractories industry access research forum, from China Association of Refractories, China mold material association representing public letter to the Office of Henan Province, and 50 large enterprises to explore developed on the refractory ore mining, industry access standards refractory materials, refractory products area.

Insiders said refractories currently facing overcapacity, industry access standards and promoting industry consolidation, improve resource utilization, and related listed companies will benefit.

In 2013, due to the decrease in the volume of orders, sales decline, cement, glass refractories enterprises compete to lower prices, payment defaults, resulting in refractories business funding constraints, some companies had to stop. China Refractory Industry Association on 52 producers of survey results show that in 2012 representing a decrease of refractories sales revenue of 4.29%, representing a decrease of 21.40 percent profit, trade receivables increased by 15.34 percent year on year.

Insiders said that the presence of resource exploitation of non-refractory industry standardization, waste and serious problem, especially blind investment and redundant construction led to the refractory industry from "structural surplus" to "full excess." And because the steel, cement, glass and other downstream industries refractory same overcapacity, profits have fallen sharply and other issues, the problem of refractory industry becomes more serious.

June 28, "to promote the progress of work in Henan refractories industry technical forum" in the new password, the meeting around the promotion of technical progress refractory industry expanded, the experts reached a basic views on the refractory industry standard enterprise 7 of 22 kinds refractory materials, 29 kinds of refractory products comprehensive energy consumption per unit of product limits and 34 kinds of refractory raw materials, product quality and technical standards were defined.

Difference between corundum and high-alumina

1. The main ingredient of 90 corundum brick is corundum and a small amount of soil in Suzhou, mullite.
2. The main ingredient of alumina bricks is high bauxite, corundum mullite and some sand.
3. The difference between them lies in how much alumina content, alumina content higher than 48% of alumino silicate refractory products 
4. Al2O3 content higher than 90%, referred corundum brick.
5. Hardness can tell the difference. To cut with a hacksaw, corundum is the hardest, followed by high aluminum and most soft clay qualitative

Refractory binders classification

一、According to the chemical nature of the organic and inorganic binders.

1. Inorganic binder:

• Silicate - calcium silicate cement, water glass, clay, etc. combined.
• aluminate - Ordinary calcium aluminate cement, calcium aluminate cement, aluminum, barium cement.
• phosphate - phosphate, aluminum dihydrogen phosphate, sodium tripolyphosphate, sodium hexametaphosphate, chrome aluminum phosphate.
• sulfate - magnesium sulfate, aluminum sulfate, ferric sulfate and the like.
• chlorides - magnesium chloride, ferric chloride, aluminum chloride and the like. 
• sols - silica sol, alumina sol, silica sol.

  2.  Organic binder:

• natural organic matter - starch, dextrin, gum arabic, pulp waste, tar, bitumen, seaweed sodium.
• organic synthesis - epoxy resins, novolac resins, resole resins, polystyrene, ethyl silicate, polyurethane resins and the like.

二、Sorted by hardening binders:

• hydraulic binders - Portland cement, aluminate cement.
• rigid gas-binding - sodium fluoride silicate, aluminum phosphate or dihydrogen phosphate plus magnesium oxide, silica plus calcium aluminate cement.
• a thermosetting binding agent - phosphate, aluminum dihydrogen phosphate, resol resin.

三、Binding at different temperatures of the temporary and permanent binders.

1. Temporary binding agents:
   

• water-soluble binding agent - dextrin, powdered cellulose, carboxymethylcellulose, lignin sulfonic acid powder and liquid materials, polyvinyl alcohol powder crystals.
• water-insoluble binding agent, - the hard bitumen, paraffin, polypropylene and the like.

 2.  Permanent bonding agent:

• Carbon binding agent - tar pitch, phenolic resin.
• aluminate cement.
• silicate binder - sodium silicate, ethyl silicate and so on.
• phosphoric acid and phosphate binders.
• salts of chloride and sulphate binders.

New fire-resistant fiber coating material technology

Refractory fiber coating technology is a new technology in the construction industry lining mechanization. Fiber construction technology spray gun through a dedicated fiber, while the binding agent is injected into the fiber diaphragm uniform flow, both external mixing one working directly sprayed onto the surface of the application environment. Forming three-dimensional network structure of products, flat, evenly firmly adhered on the work surface.

Its flexibility is also more prominent in the construction and thickness of the fibers to give the corresponding temperature of the device according to the use environment. In short construction technology fiber coating is made up of conventional construction defects fiber products, fiber products to improve the overall performance of the replacement products.

Application Performance of refractory fiber coating material technology

1.          Lining spray technology has also received a one-time multi-layer composite liner features a seamless whole, bulk cotton three-dimensional network structure formed in the coating process, the fiber orientation effectively avoid shrinkage at high temperatures, make up the traditional backward refractory fiber layer Shop, overlay, veneer and other construction process unit indirect seam defects. Completely eliminates channeling channeling gas fire dew point corrosion damage to the furnace shell and anchors, and strengthen the overall sealing, insulation and fire resistance.

2.         Application refractory fiber coating technology can greatly reduce the resources and costs, especially for some flexibility in the face of complex shaped construction, and to ensure the rigor of the adjacent binding sites, but also to reduce the use of multiple anchors accessories design reduces installation complexity. Construction technique than conventional refractory fiber lining with greater intensity, uniform and smooth lining overall sturdiness. Anti-erosion resistance, corrosion sexuality has greatly improved.

3.         Development and application of new coating binders more of its advantages. Refractory fibers and binders full glued to form a three-dimensional space as a whole, with a binding agent to form a bond network structure than conventional refractory fiber carpets, carpet tile overlay, folded pieces of low thermal conductivity, to ensure construction quality lining and get better surface brightness

4.         Refractory fiber coating technology to better reflect its economic value. It can be graded according to the distribution of a composite material temperature heat transfer mechanism. So that the temperature of the lining material, the thickness of the total cost tends to be economically rational design. Perfectly formed to achieve the overall composite and hybrid materials. Secondary processing also save a lot of manpower and material resources of refractory fibers.

Physical properties of refractories

Physical properties of refractories include structural properties, thermal properties,

mechanical properties, performance and operational performance.

• Structural performance of refractories include porosity, bulk density, water absorption, air permeability, pore size distribution.

• Thermal properties include thermal conductivity refractory, thermal expansion coefficient, specific heat, heat capacity, the thermal diffusivity, thermal emission rate

• Mechanical properties of the refractory included compressive strength, tensile strength, flexural strength, torsional strength, shear strength, impact strength, abrasion resistance, creep resistance, bond strength, elastic modulus.

• Performance of refractories include refractoriness, RUL,
  
  heavy firing line changes, thermal shock resistance, slag resistance, acid resistance, alkali resistance, resistance to water resistance, corrosion resistance to CO, conductivity, oxidation resistance and so on.

• Workability of refractory including consistency, slump, fluidity, plasticity, adhesion, elasticity, coagulating, hardening and the like.

Introduction of special refractories

Special Refractories is a new inorganic non-metallic materials developed on the basis of traditional ceramic and refractory materials in general on. It has the following characteristics: melting point, high purity, good chemical stability and thermal shock resistance.

Special refractories include high melting point oxides and refractory compounds and derived therefrom, metal ceramics, high temperature coatings,

high temperature fiber and reinforced materials.

Compared with traditional ceramics and refractories, special refractories, high purity, high melting point, good electrical, thermal, mechanical and chemical properties, Thus, can use for high precision and advanced science and technology; in the manufacturing process, raw materials generally after burned. In addition to the traditional method of molding, but also using new technology vapor deposition, hot and so on. Micron powder molding compound material is calcined at high temperatures and require a protective atmosphere, the article can be made thin (translucent).

Unshaped refractories and classification

Unshaped refractories is composed by reasonable graded granular and powdered  together with a binding agent. molding and baking without the direct use of refractory materials.

Unshaped refractory variety, which are classified as follows:

• By technology features Category: castable, plastics,
  
  ramming mixes, injection materials, cast materials, fire clay, painting materials.
• By raw material classification: siliceous, clay, high alumina, magnesia, dolomite, chrome, with chrome and so on.
• By binders species classification: sodium silicate combined aluminate cement bonded silicate combined tar combination, such as phenolic resin bond.