JP6162050B2 - Effective use of sapphire scrap - Google Patents

Description

The present invention relates to a method for effectively using sapphire processing waste. More specifically, sapphire processing waste, which is usually discarded by landfill disposal, etc., is fired containing 20% by mass or more of anorthite (CaO.Al ₂ O ₃ .2SiO ₂ ) useful as a mixed material such as cement. It provides an effective utilization method as a raw material for manufacturing products.

Sapphire is a crystal of Al ₂ O ₃ and is widely used as a material for industrial products such as electronic devices because of its excellent mechanical, thermal properties, chemical stability, and light transmission. It is also used as.

  Sapphire processing waste generated in the process of manufacturing LED substrates from single crystal sapphire is partly recycled as raw material for single crystal sapphire, but powder generated when cutting, grinding or polishing the material is cut. Impurities from the machine blades and grinding fluid are mixed in and cannot be recycled and are discharged as waste. The amount generated is said to be about 500 tons per year and is expected to increase in the future, but at present it is disposed of in landfills without being effectively used.

  On the other hand, in connection with recent global environmental problems, effective use of waste, by-products, etc. has become an important issue. Taking advantage of the characteristics of the cement industry and cement production facilities, it is considered effective from the viewpoint of safe and mass disposal to effectively use or treat waste as raw material or fuel during cement clinker production.

However, among wastes, by-products, etc., coal ash, municipal waste incineration ash, blast furnace granulated slag, blast furnace slow-cooled slag, etc., especially coal ash, have an Al ₂ O ₃ content as compared with ordinary cement clinker composition. Many. Therefore, when the amount of such wastes, by-products, etc. used is increased, the content of the aluminate phase corresponding to the interstitial phase in the cement clinker component is increased, which affects the cement physical properties. Accordingly, the amount of waste, by-product, etc. used as a cement clinker raw material is restricted by the amount of the Al ₂ O ₃ component. Under such circumstances, a technique has been proposed in which a baked product containing coal ash as a main raw material and containing anorthite (CaO · Al ₂ O ₃ · 2SiO ₂ ) is used as a cement mixture or fine aggregate ( It is promising as a new treatment method for wastes, by-products and the like.

Japanese Patent No. 4494743 Japanese Patent No. 4456832

  The present invention seeks to provide an effective method of using sapphire processing waste that has often been discarded by landfill disposal as described above.

The present inventors have conducted intensive research to solve the above problems. And 97% or more of the sapphire processing waste is made of Al ₂ O ₃ and can be used as an aluminum source for anorthite raw material, C and organic matter which are minor components other than aluminum can be thermally decomposed at high temperature, The inventors have found that other trace metals are dissolved in anorthite and have completed the present invention.

  That is, the present invention is a processing method of processing waste discharged at the time of processing sapphire, the processing waste is mixed with at least both coal ash and a calcium source, and calcined to have an anosite content of 20% by mass or more. It is a processing method of the sapphire processing waste made into this baked product.

  According to the treatment method of the present invention, it is possible to obtain a fired product containing sapphire processing waste as a raw material and containing 20% by mass or more of anorthite useful as a cement mixture or fine aggregate. Therefore, a large amount of waste can be treated as compared with the prior art, which is an advanced method for dealing with environmental problems.

The processing method of this invention mixes sapphire processing waste, coal ash, and calcium containing raw material powder, and bakes this. The said sapphire processing waste can use what generate | occur | produces when cut | disconnecting, grinding, and grinding | polishing at the process of producing LED chip from the ingot of a sapphire single crystal. The main component of the sapphire processing waste is 97 to 99% by mass of Al ₂ O ₃ in the solid content, C as a minor component derived from the blade of the cutting machine and the grinding fluid, 1 to 2% by mass of organic matter, Including about 1% by mass or less of metal.

  As the cutting, grinding, and polishing steps, the upper and lower ends of the ingot are cut and the sapphire core is manufactured by cylindrical grinding, the sapphire core is cut into a thin plate with a multi-wire saw, and the both sides of the thin plate obtained by the cutting. Alternatively, there is a processing to a substrate by single-side polishing. In the present invention, any processing waste discharged from any process can be used.

  Since cutting or polishing of sapphire is often performed using a grinding liquid in which water or a small amount of an organic substance is dissolved in water, sapphire processing waste is usually included in the discharged slurry discharged at that time. It is possible to obtain anorthite by mixing the discharged slurry and other raw materials and firing, but from the viewpoint of handling and effective use of thermal energy, the discharged liquid is separated into solid and liquid, and sapphire processing waste It is desirable to use as a raw material what was dried, grind | pulverized, and powdered after collect | recovering as solid content. The solid-liquid separation may be a known method, and can be performed by, for example, a filter press, vacuum filtration, belt press, centrifugation, or the like.

In the present invention, in order to obtain a fired product containing 20% by mass or more of anorthite (CaO · Al ₂ O ₃ · 2SiO ₂ ), coal ash is used as at least a SiO ₂ source in addition to the sapphire processing waste. Of course, as is well known, coal ash has included many _Al 2 _{O 3} in addition to SiO _2, because the _Al 2 _{O 3} is also a component constituting the anorthite, it can be effectively utilized.

The said coal ash can use well-known coal ash, ie, what is discharged | emitted from a thermal power plant etc., without being restrict | limited in particular. Common coal ash contains 35 to 76% by mass of SiO ₂ as a main component, 17 to 40% by mass of Al ₂ O ₃ , and other minor components to form CaO, Fe ₂ O ₃ , MgO, and TiO _2. , Na ₂ O, K ₂ O and the like. Coal ash is in the form of powder as the term indicates.

  In the present invention, a calcium source is used as a raw material in addition to the sapphire processing waste and coal ash in order to obtain a fired product containing 20% by mass or more of anorthite. In the present invention, the calcium source means that the CaO ratio in the ignition residue at 975 ° C. is 40% by mass or more.

As the calcium source, CaO, CaCO ₃ , Ca (OH) ₂ powder, and the like can be used. Limestone (CaCO ₃ ) is preferably used because of its availability. In addition, a powder (cement clinker raw material) whose main component is limestone and whose chemical composition is adjusted so as to produce a Portland cement clinker when fired alone can be used.

In the present invention, in order to obtain a fired product containing 20% by mass or more of anorthite (CaO · Al ₂ O ₃ · 2SiO ₂ ), in addition to the sapphire processing waste, coal ash and calcium source, as a raw material for cement clinker Various known raw materials may be further mixed and used. Such raw materials include silica, clay, blast furnace slag, steelmaking slag, non-ferrous iron slag, waste white clay, bottling, purified water sludge, paper sludge, construction generated soil, municipal waste, municipal waste incineration ash, sewage sludge, sewage sludge incineration ash Etc.

In the present invention, in order to obtain a higher-anorthite content baked product, the raw material after mixing, the SiO ₂ thirty-four to sixty-three wt%, the _Al 2 _{O 3 22~42%} by weight, a CaO 12 to 28 preferably to include mass%, a SiO ₂ 40 to 55 wt%, the _Al 2 _{O 3} 27 to 37 wt%, and more preferably comprise a CaO 15 to 23 wt%.

  Whether or not the chemical composition of the ignition residue of the raw material is within the above range is determined according to JIS R5202 “Portland cement chemical analysis method” or JIS R5204 “cement fluorescent X-ray analysis method”. Measurement and confirmation may be performed by a compliant method. Further, ignition at 950 ° C. is performed according to “5. Determination of ignition loss” in JIS R5202.

  In the present invention, the firing temperature of the raw material of the fired product is 1000 ° C. or higher. When the firing temperature is less than 1000 ° C., the mineral is not sufficiently generated. A more preferable firing temperature is 1150 ° C. or higher. In addition, when the firing temperature exceeds 1400 ° C., the raw material melts and vitrifies, making it difficult to produce the mineral. Accordingly, the maximum temperature during firing is 1400 ° C. or lower, and preferably 1350 ° C. or lower.

  Although the firing time depends on the firing temperature, it is generally 0.5 to 10 hours, preferably 1 to 5 hours.

  It is desirable that each raw material be powdered during firing. The degree of fineness may be the same as that of the cement clinker firing raw material, and generally 90 micron sieve residue is about 20 to 30%.

  The firing method is not particularly limited as long as it is an apparatus capable of obtaining the above temperature, but from the viewpoint that an existing Portland cement production facility can be used, NSP kiln, high temperature heating such as cement kiln represented by SP kiln, etc. The apparatus which can be used can be used conveniently. Moreover, it is preferable to use the said cement equipment also from a viewpoint of mass production or mass processing.

In the present invention, a fired product containing 20% by mass or more of anorthite (CaO · Al ₂ O ₃ · 2SiO ₂ ) is obtained. Preferably, the anorthite is 50% by mass or more, more preferably 70% by mass or more.

The fired product produced in the present invention can be made into a hydraulic composition by pulverization with Portland cement clinker and gypsum, or pulverization individually and then mixing. The mixing ratio of the fired product is generally 1 to 50 parts by mass, preferably 1 to 30 parts by mass with respect to 100 parts by mass of Portland cement clinker. As the gypsum to be used, known gypsum can be used without particular limitation for producing cement such as dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. The amount of gypsum added is preferably such that the amount of SO ₃ in the hydraulic composition is 1.5 to 5.0% by mass, such that the amount is 1.8 to 3.0% by mass. Is more preferable. For the method of pulverizing the fired product, Portland cement clinker and gypsum produced by the production method of the present invention, known techniques can be used without particular limitation. As the Portland cement clinker, known ones can be used without any particular limitation on the production method and composition.

  Further, the hydraulic composition may be further appropriately mixed, mixed and pulverized with a blast furnace slag, a siliceous mixed material, fly ash, calcium carbonate, limestone and other mixed materials and a grinding aid. Further, chlorine bypass dust or the like may be mixed.

The fineness of the hydraulic composition is not particularly limited, but is desirably adjusted to 2800 to 4500 cm ² / g.

  Further, if necessary, blast furnace slag, fly ash or the like can be mixed after pulverization to obtain blast furnace slag cement, fly ash cement or the like.

  The fired product of the present invention may be used as a raw material for cement production outside the JIS standard or a cement-based solidified material.

  Furthermore, the fired product obtained by the production method of the present invention can be used as a fine aggregate for producing mortar and concrete by pulverizing the particles to 2.5 mm or less by a sieving method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples.

  The sapphire processing waste was generated when a sapphire single crystal ingot was cut into a wafer. The coal ash used was discharged from a thermal power plant in Japan. As the calcium-containing powder, a cement clinker raw material mainly composed of limestone was used. The chemical analysis results (fluorescence X-ray analysis) of these raw materials are shown in Table 1 below.

  A mixture of 14% by mass of sapphire scrap, 50% by mass of coal ash and 36% by mass of cement clinker raw material was calcined at 1250 ° C. for 0.5 hour to obtain a calcined product (Example 1). A mixture of 7% by mass of sapphire processing waste, 54% by mass of coal ash, and 39% by mass of cement clinker raw material was calcined at 1100 ° C. for 0.5 hour to obtain a calcined product (Example 2). The amount of anorthite contained in the fired product was determined by Rietveld analysis using the chemical composition by fluorescent X-ray analysis and the internal standard of powder X-ray diffraction. The results are shown in Table 2.

  In addition, coal ash alone (Reference Example 1) or a mixture of 58% by mass of coal ash and 42% by mass of cement clinker raw material (Reference Example 2), calcined at 1100 ° C. for 0.5 hour, Got. These evaluation results are also shown in Table 2.

Claims (2)

  A processing method for processing waste discharged during processing of sapphire, wherein the processing waste is mixed with at least both coal ash and a calcium source and fired to obtain a fired product having an anosite content of 20% by mass or more. Processing method of processing waste. Machining debris, processing method according to claim 1 which is a solid component obtained by solid-liquid separation discharge slurry discharged when forming the sapphire single crystal on the LED substrate.