CN86103199A

CN86103199A - Amorphous graphite sand

Info

Publication number: CN86103199A
Application number: CN86103199.7A
Authority: CN
Inventors: 颉立生
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-05-01
Filing date: 1986-05-01
Publication date: 1987-01-31
Also published as: CN1006526B

Abstract

The present invention is a kind of foundry sand, and its main component is a cryptocrystal shape graphite.It is processed by natural amorphous graphite mineral, thus than Delanium sand considerably cheaper, and with various sand facies ratios commonly used such as quartz sand, it has characteristics such as high thermal conductivity, high refractoriness, high chemical stability and low thermal expansion again.Available its replacement Delanium sand and zircon sand, magnesia, chromite sand etc. can be used for the casting of high-melting-point alloy and easy oxidation metal such as alloys such as magnesium, titanium, and to air-tightness, the casting of the various foundry goods that grain size etc. have higher requirements.

Description

Amorphous graphite sand

The present invention is a kind of foundry sand, the roughing sand of using when making blending type, core compound.

So far, the main application of amorphous graphite in foundry industry, be with powdery as coating, dressing or the type of type, core, a kind of auxiliary material in the core compound, and never have this kind mineral are processed into the precedent that sand shape is made foundry sand.The present invention is processed into the sand shape material with natural amorphous graphite mineral, its content of graphite is below 90%, the roughing sand of using as blending type, core compound in Foundry Production is used as type, the core sand making the casting special metal of some performance and require special foundry goods.Particularly, this kind sand not only can be processed into the higher ore of graphitic carbon content, and can with at present in the amorphous graphite processing industry generally as lean ore and mine tailing abandon, graphitic carbon content processes at the ore below 65%.

For a long time, the appearance of and cast metal that fusing point higher more active along with performance, along with improving constantly that casting quality is required, performance to molding sand and casting mold has also constantly proposed new requirement, therefore, seeking the new foundry sand outside traditional quartz sand always, just as zircon sand, magnesia, chromite sand, electro-corundum, olivine sand and China the seventies once to conduct vigorous propaganda the appearance of limestone sand of promoting etc. indicated.These emerging foundry sands on performance, price, source, exist some known weak points, and for example the reuse of limestone sand is poor, and foundry goods easily produces pore and shrink mark etc.; The zircon sand price is per ton up to thousands of units, chromite sand China almost completely relies on import, or the like, the another kind of novel casting sand of people's research is to have the be graphitic carbon of higher refractoriness, thermal conductivity, chemical stability or the like a series of ideal performances or the carbon sand of coke carbon manufacturing far away.This brand-new foundry sand, the desirable foundry sand of performance when not only becoming the casting of easy oxidation metal such as high-melting-point alloy, magnesium, titanium or alloy, and, because its high thermal conductivity, can make type, the core of ability with it, to obtain at the foundry goods that has higher requirements aspect air-tightness or the fine and closely woven degree of crystal grain with chill casting casing metal; More special is that type, the core of such Quench type owing to have good deformability, gas permeability and collapsibility, reach the characteristics that are not subjected to batch and size restrictions, so have purposes widely than rigidity Quench type casting molds such as metal mold, graphite moulds.

But, research to carbon sand, mainly concentrate on artificial coke always, on the artificial high-purity material such as Delanium, as BP 798249, United States Patent (USP) 2830342,2830913 addressed be processed into petroleum residual oil, contain coke carbon more than 98% calcining fluid coke sand and the applicable cases on Foundry Production, U.S. Philadelphia Frankfort munitions factory with the artificial electrographite powder of purity more than 98% as magnesium-lithium alloy foundry sand, and China's Dalian shipyard with high-purity Delanium goods chip as the core sand of large-scale diesel engine cylinder sleeve casting etc., these materials are not only originated limited, and cost an arm and a leg, as artificial electrographite powder, price per ton is up to thousands of units, calcining fluid coke sand is raw material with the petroleum residual oil, and price is also expensive.Therefore, it is very little that these sand are promoted practical possibility in Foundry Production.

Purpose of the present invention, just be to utilize amorphous graphite this abundant, at present the natural minerals of excess supply capacity is arranged, make a kind of inexpensive, the source is abundant and foundry sand that performance can be satisfied the demand equally.

Most amorphous graphite ores, except that cryptocrystal shape graphite, main argillaceous class mineral, and graphite grains is embedded among the clay mineral dispersedly, the structural form of form disperseing structure, promptly graphite grains by the adhesion of clay mineral institute get up, so ore not only can obtain the grain shape of sand shape when fragmentation, and under the Foundry Production condition, repeatedly reuse.Obviously, if other mineral except that cryptocrystal shape graphite and clay mineral in the ore, as the content of phanerocrystalline texture shape graphite, free carbon dioxide, alundum (Al, feldspar etc. the more, just then the grain shape of prepared sand and reuse are poorer.Therefore, the ore that is used for making amorphous graphite sand contains the amount of these impurity, should be low as far as possible, be advisable to be no more than 20%, simultaneously, for physical and chemical performance and the granule strength that guarantees amorphous graphite sand, graphitic carbon and clay also must keep certain content in the ore, in general, graphitic carbon content be higher than 30%, clay content is advisable to be higher than 10%.

Ore is after classifying through primary election and by phosphorus content, perhaps making for before being used to prepare the roughing sand of core mixture, must be through calcination process, with remove its CLAY MINERALS AND THEIR SIGNIFICANCE contained in conjunction with water, therefore, sintering temperature is according to contained clay mineral kind, and promptly the decomposition temperature of this kind clay-bound water (CBW) is determined.In traditional amorphous graphite processing industry, no matter be processing graphite powder or granular graphite, ore was only removed the oven dry of adsorbed water and is handled before pulverizing, will not remove in conjunction with water.

The granularity of amorphous graphite sand, be advisable to 100 orders to occupy 6 orders, it is a kind of in the particle size range thus, can also several granularities constitute, but under any circumstance, all tackle the content of the content comparison oversize of screenings and do stricter qualification, because the proportion of amorphous graphite is more much smaller than various traditional sand, screenings content the more causes that the possibility of black dust pollution is just bigger.For same consideration, being narrower than 100 purpose amorphous graphite crushed materials should not use as foundry sand.

Produce the technological process of amorphous graphite sand and can adopt two kinds of schemes: 1. adopt the similar disintegrating apparatus that uses when producing synthetic quartz sand, wait as jaw formula, hammer mill and pulverize, sieve with mechanical picker again.2. preparation and traditional graphite powder, the production of granular graphite with this molding sand combines, and sieves out the do foundry sand of 6 orders to 100 order scopes, and 6 orders are above, 100 orders are following then as granular graphite and graphite powder.

Amorphous graphite sand is also pressed the content classification of graphitic carbon simultaneously except that classifying by particle size, graphitic carbon content is higher, and its performance just more approaches Delanium sand, otherwise more approaches traditional sand such as quartz sand, in this way, in the hope of making full use of resource, rationally selects molding sand for use.

One of characteristics of the present invention are, not only can be higher with grade, and, also can utilize graphitiferous carbon to be low to moderate 30% poor value and make extremely useful amorphous graphite sand.In traditional amorphous graphite processing industry, the ore of carbon containing below 65% generally regarded lean ore as and abandoned need not.

Artificial carbon element sand facies ratio with high-purities such as electrographite powder, amorphous graphite sand removes has low price, outside the resourceful advantage, its performance also has been enough to satisfy the needs of Foundry Production, many performances of highly purified artificial electrographite powder are compared then high too much with the actual needs of Foundry Production, fusing point as high purity graphite can be up to 3850C, this all is unnecessary concerning any casting alloy, simultaneously, do in the practice of foundry sand at employing high-purity graphous graphite powder so far, all add the non-graphite materials such as clay of a large amount again as one of core mixture component, as seen select for use high purity graphite to make foundry sand,, also be unreasonable only with regard to technical speech.

With traditional sand facies ratios such as quartz sands, amorphous graphite sand has following important practical performance:

One. high thermal conductivity and cooling capacity

The characteristics that have high thermal conductivity according to graphite, selection is than the amorphous graphite sand of high carbon content and bigger type, core process, just can reach the purpose of raising type, core cooling capacity, acquisition air-tightness in a kind of economical and convenient ground is good, the method for the foundry goods of compact crystallization thereby created, with compare for the method that same purpose adopts graphite mould, metal mold, supercharging casting, low pressure casting and the clear 57-202943 of Japan Patent to be provided is provided, method of the present invention is economical and convenient not only, and the scope of application is much bigger.

High thermal conductivity also makes the oven dry and the cool time of type, core oven dry and molding sand shorten greatly.

Two. high refractoriness

Amorphous graphite sand with carbon containing 80% is an example, and its refractoriness can be enough to satisfy the requirement of nearly all cast metal to the molding sand refractoriness up to 2000C, is that any traditional natural minerals sand institute is inaccessible.

Three. high chemical stability

Because graphite belongs to chemically neutral, be excellent so the chemical stability of amorphous graphite sand always has traditional mineral sand of acid, alkalescence.Chemical scab when amorphous graphite sand can be used for the casting of easy oxidation metal effectively and prevent the common metal casting.

Four. be difficult for being the performance of metal liquid infiltration

This performance of amorphous graphite sand makes and needn't add coal dust in type, core compound, removes in die cavity into coal dust or graphite powder, to type, core wall brushing graphite powder, still can prevent from preferably to invade because of molten metal to ooze the scab that causes.

Five low thermal expansions

Six no sand and dust pollutions

Seven antiquated sands can be used as the fuel utilization, so no antiquated sand is toppled over or the stacking problem.

With the cast sample of cast steel, cast iron, cast aluminium of amorphous graphite sand mold, with under the identical situation of other conditions with the comparing of common silica sand casting, its Metallographic Analysis shows that the former grain size can be greatly improved.

With the withstand voltage cast aluminium pipe fitting of ZL105 of amorphous graphite sand coring casting, than what cast with the quartz sand coring, its withstand voltage properties has improved greatly.

Make the thick big cast copper aluminum casting of type, core casting with amorphous graphite sand, its pinhole rate has improved greatly.

With the core that the clay of the amorphous graphite sand of carbon containing 75% and 10% is mixed and made into, scab does not take place in foundry goods with 1520～1550 ℃ pouring temperatures casting 42CrMo steel thickness 150mm completely.It is worthy of note simultaneously, when adopting amorphous graphite sand to be molding sand, even light be scab or burning into sand appear in foundry goods, owing to the hardness of this sand is lower, so still can carry out machining.

With the easy oxide alloy of amorphous graphite sand manufacturing, during as the type of titanium alloy, magnesium alloy etc., core, not only the high chemical stability owing to this sand need not to add the anti-chemical reactant that fluoride, sulfonated bodies etc. can cause public hazards in core mixture, and because the cooling capacity of type, core is big, so can also significantly reduce the common deficiency of this class foundry goods simultaneously, can improve the mechanical performance of foundry goods as ， And such as shrinkage porosite, pin holes.

Revisal 86103199

After the preceding revisal of the capable revisal of file name page or leaf

The type of the Quench type that specification 25 is such is because this Quench type type, core

Core, because ... and do not have ... and be not subjected to foundry goods

Be subjected in batches ... in batches

11 contain coke carbon 98% above fixed carbon content more than 94%

36 free carbon dioxide free silicon dioxides

Claims

1, the carbon sand used of foundry industry mainly is made up of graphite, and it is characterized in that: be the sand shape material that processes with natural amorphous graphite mineral, its content of graphite is below 90%.

2, by the described amorphous graphite sand of claim 1, it is characterized in that natural amorphous graphite mineral except that containing cryptocrystal shape graphite, key component is clay class mineral, and graphite grains is embedded among the clay mineral structural form of formation dispersion structure dispersedly.

3, by claim 1,2 described amorphous graphite sands, it is characterized in that ore before making molding sand by fragmentation, or after fragmentation, necessary through roasting, contained with the clay mineral of removing wherein in conjunction with water.

4, by claim 1,2 described amorphous graphite sands, it is characterized in that: granularity is in 6 order to 100 order scopes.

5, by the described amorphous graphite sand of claim 3, it is characterized in that granularity is in 6 order to 100 order scopes.