KR910006777B1 - Insulation material for molten metal - Google Patents

Abstract

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Description

Insulation material for molten metal

A first object of the present invention is to provide a heat insulating material for coating the surface of molten metal to prevent cooling and oxidation of the metal from the surface.

A second object is to effectively prevent pollution caused by using paper sludge which is waste material generated in the papermaking process.

Insulating materials for molten metals have been used in the past for organic materials such as rice hulls, grain husks, wood flour and their carbonized materials, or refractory materials such as diatomaceous earth, slate, black alumina and silica sand, and aluminum, magnesium There exists an exothermic heat insulating material which contained oxidizing agents, such as iron oxide nitrate, in a combustible metal.

Each of the conventional thermal insulation materials, such as the following drawbacks, that is, the organic material and its carbide system has a short thermal insulation time, so it requires a large amount of input for long-term insulation and dust generation is not good for environmental hygiene. In addition, the refractory system is not good thermal insulation due to the endothermic heat and heat exothermic insulation is effective for a short time, but lacks in sustainability. Papermaking sludge, when discharged into a river or sea, accumulates in the riverbed or seabed, and causes severe pollution.

The present invention has been developed to solve the above problems. That is, the molten metal thermal insulation material of the present invention is formed of a material calcined by adding at least one organic or inorganic water-soluble binder to the paper sludge discharged from the papermaking process, the paper sludge containing lignin, filler, and carbon content of 5% by weight. It is characterized in that the granularity of the apparent specific gravity of 0.5 or less and the particle diameter of 20mm or less.

The sludge discharged from the papermaking process is a substance contained in the waste liquid when the pulp is adjusted or during the papermaking process of forming a tangled layer of paper fibers and dehydrating and drying it. Dehydration of this waste liquid as a dehydrator yields a dehydrated product having a moisture content of 60 to 90% by weight and a solid content of 10 to 40% by weight.

At least one organic or inorganic water-soluble binder is added thereto to harden the granules and calcined at a temperature of about 300 to 800 ° C.

It is preferable to use a rotary kiln for baking. At this time, the organic matter in the material is partially carbonized without completely burning to obtain a granular calcined material having a carbon content of 5% by weight or more, an apparent specific gravity of 0.5 or less and a particle diameter of 20mm or less. Organic components such as pulp fibers and ligrins in paper sludge and talc, clay, activated clay, etc., which are included as fillers, are important components to improve the thermal insulation properties of plastic materials. Organic or inorganic water-soluble binders are intended to prevent breakage and to maintain granular form and strength in the process from firing to storage, transport and use as thermal insulation. Organic binders include dextrin, CMC, lignin sulfonic acids, polyvinyl acetate, emulsion, polyvinyl alcohol, polyacrylic acid, isobutylene maleic acid, and inorganic water-soluble binders such as activated clay, clay, bentonite, aqueous silica sol, alkali silicate aqueous solution. , Aqueous solution of phosphate of ammonia or aluminum. One or more kinds of such binders may be used.

The carbon content of the calcined material is 5% by weight or more because at 5% by weight or less, the heat of carbon cannot be sufficiently used when the molten metal is coated, resulting in poor thermal insulation. If the apparent specific gravity is 0.5 or less, the heat retention is extremely lowered when it exceeds 0.5.

If the particle diameter is 20 mm or less, if the thickness exceeds 20 mm, the space between the particles of the heat insulating material becomes large and the heat retention is lowered.

EXAMPLE

0.8 wt% of sodium silicate was added to the paper sludge discharged from the papermaking process and calcined at a temperature of about 500 ° C. in a rotary kiln to prepare a calcined material having a carbon content of 13.4%, an apparent specific gravity of 0.27, and a particle diameter of 2 to 7 mm. At this time, the loss on ignition was about 24.5 wt%.

The material thus obtained was coated with a 40 mm thickness on the molten surface of the 60 ton ladle. At this time, the result of measuring the molten metal temperature in the ladle showed that the temperature drop was 80 ° C. after the addition of the thermal insulation material at 80 ° C. after the addition of 1600 ° C. As a result of using the carbonized chaff under the same conditions, the temperature drop was 76 ° C., and it was confirmed that the thermal insulation of the present invention was excellent in heat retention.

Moreover, as a result of using the heat insulating material of this invention for ingot, the heat insulation effect of an ingot was improved, and the recovery rate of ingot rolling improved 1.1%.

The thermal insulation material of the present invention is burned or volatilized when burned and lost carbon and residual organic matter, that is, loss of ignition of 40% by weight or less, ash of the combustion residue is 60% by weight or more, and the burning rate of the carbon and residual organic matter is increased. It is slow and has excellent thermal insulation of combustion residue.

In the present invention, the combustion material is used alone as a heat insulating material for molten metal, but even when mixed with other materials containing a known heat insulating material exhibits a sufficient effect.

Claims (1)

5% by weight or more of carbon content, 0.5 or less in particle size and 20mm in diameter by molding from paper material containing at least one organic or inorganic water-soluble binder to paper sludge containing pulp fibers and lignin fillers discharged from the papermaking process. Molten metal heat insulating material characterized by the following moldings.