JP2007136540A

JP2007136540A - Burning prevention sand and supply sand used in furan self-hardening closed method

Info

Publication number: JP2007136540A
Application number: JP2005358238A
Authority: JP
Inventors: Keiji Miyauchi; 啓次宮内; Yoshiaki Takemoto; 義明竹本
Original assignee: MCT KK
Current assignee: MCT KK
Priority date: 2005-11-15
Filing date: 2005-11-15
Publication date: 2007-06-07

Abstract

<P>PROBLEM TO BE SOLVED: To provide mixed sand between silica sand and Ni slag sand used in a furan self-hardening closed method which does not obstruct the hardening of a mold. <P>SOLUTION: The invention is a refractory mixture used in a furan self-hardening method, and a coarse, spherical refractory produced by the weathering of molten slag essentially consisting of 2MgO-SiO<SB>2</SB>and generated upon Ni refining, which has a grain size in the range of 0.08 to 3.50 mm and AFS fineness number in the range of 8 to 35, and whose surface is treated with organic acid is beforehand mixed into silica sand in the weight ratio of 10 to 70%, and it is blended so as to be applied to the molding of a mold as it is. By beforehand subjecting the Ni slag sand to acid treatment, even if the mixing ratio of the Ni slag sand is increased, the obstruction of the hardening in a furan resin can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

産業上の利用分野Industrial application fields

本発明は、鋳物製造用の鋳型を形成する鋳物砂に関する。更に詳しくは、本発明は、従来使用されているクロマイト砂、ジルコン砂やムライトに代わって、焼着防止用として新しい構成の焼付防止用混合砂を提供し、これらの持つコスト高や廃棄物規制を改善できる新規の混合砂を提供する。 The present invention relates to foundry sand forming a casting mold. More specifically, the present invention provides a new structure of anti-seize mixed sand for preventing seizure in place of conventionally used chromite sand, zircon sand and mullite. Provide new mixed sand that can improve

一方、使用砂を回収して再利用する有機自硬性クローズド法においては、これらの特殊砂の蓄積を改善し、回収再生砂全体の焼着を軽減できる新規の補給用混合砂を提供する。 On the other hand, in the organic self-hardening closed method in which used sand is collected and reused, a new replenished mixed sand that improves the accumulation of these special sands and can reduce the seizure of the entire recovered and reclaimed sand is provided.

従来の技術及び発明が解決しようとする課題Problems to be solved by the prior art and the invention

従来の有機自硬性クローズド法では、世界的にもフラン自硬性法が最も一般的である。このフラン自硬性法においては、天然の珪砂が使用されてきているが、課題として珪砂の熱膨張が大きいために、熱的条件が厳しい部所に溶鉄が浸透して焼着が発生して砂落とし工数がかかる。その解決方法として、旧ＪＩＳ６号〜７号の細粒のクロマイト砂やジルコン砂やムライト系人工砂のような高価で特殊な低膨張砂を別途混練して部分的に適用しているのが実状である。 In the conventional organic self-hardening closed method, the furan self-hardening method is the most common in the world. In this furan self-hardening method, natural silica sand has been used. However, due to the large thermal expansion of silica sand, molten iron penetrates into places where thermal conditions are severe and seizure occurs and sand is generated. It takes time to drop. As a solution to this problem, it is a fact that expensive special low expansion sand such as fine chromite sand, zircon sand and mullite artificial sand of old JIS Nos. 6 to 7 are separately kneaded and applied partially. It is.

また、このような特殊な低膨張砂は高価である一方、比重が大きいため、リサイクル法での回収砂中に蓄積しやすく、回収砂の性状が変化する。そのため多く使用出来ず、慎重な回収砂管理が必要となっている。 Further, such special low expansion sand is expensive, but has a large specific gravity, so that it easily accumulates in the collected sand by the recycling method, and the properties of the collected sand change. For this reason, it cannot be used much and careful management of the collected sand is required.

一方、フラン自硬性クローズド法においては、最近ニッケル鉱滓の熔融スラグから得られた２ＭｇＯ・ＳｉＯ_２を主成分とする人工砂が注目されている。粗目の人工砂を補給砂として使用して蓄積させて、持砂の約３０〜４０％に達するまで補充し、回収、再製砂の鋳型強度を向上させてコストダウンを計り、熱膨張を低下させて焼着等の品質向上を計るる方法が採用されてきている。On the other hand, in the furan self-hardening closed method, artificial sand mainly composed of 2MgO · SiO ₂ obtained from a molten slag of nickel ore has recently attracted attention. Coarse artificial sand is accumulated as supplementary sand, replenished until it reaches about 30-40% of retained sand, and the mold strength of recovered and remanufactured sand is improved to reduce costs and reduce thermal expansion. A method of improving quality such as baking has been adopted.

以上のことは、特願２００５−１９４３２０で既に紹介されているが、ただし、このフラン自硬性法において、この２ＭｇＯ・ＳｉＯ_２を主成分とする人工砂（以下Ｎｉ鉱滓砂と言う）はアルカリ性であるため、珪砂中のＮｉ鉱滓砂が約１０％を越えると、酸硬化剤によるフラン樹脂の硬化を阻害して従来の健全な鋳型強度発現が得られない。The above has already been introduced in Japanese Patent Application No. 2005-194320. However, in this furan self-hardening method, the artificial sand mainly composed of 2MgO.SiO ₂ (hereinafter referred to as Ni ore sand) is alkaline. For this reason, when the Ni ore sand in the silica sand exceeds about 10%, the curing of the furan resin by the acid curing agent is inhibited, and the conventional sound mold strength expression cannot be obtained.

焼着防止用には、従来の珪砂に約３０〜４０％のＮｉ鉱滓砂を混合して使用することが必要であり、この場合鋳型の鋳型強度発現が阻害されるため樹脂と硬化剤量を増加しなくてはならないため、コスト高とガス欠陥の対策が必要となる。 In order to prevent seizure, it is necessary to mix conventional silica sand with about 30 to 40% Ni ore sand. In this case, since the mold strength of the mold is inhibited, the amount of resin and curing agent is reduced. Since it must increase, cost is high and measures against gas defects are required.

珪砂とＮｉ鉱滓砂が混合された回収砂によるフラン自硬性クローズド法においては、定量切り出しによりＮｉ鉱滓砂を補給する場合は２〜３％であるため影響は殆どないが、フレコンバッグ等により一度に大量にバラシ場で補給する場合も多く、この場合Ｎｉ鉱滓砂が偏析して１０％越える場合鋳型強度発現が阻害される恐れがある。 In the furan self-hardening closed method using recovered sand in which silica sand and Ni ore sand are mixed, there is almost no effect when replenishing Ni ore sand by quantitative cutting, but there is almost no effect at once, such as with a flexible container bag. In many cases, the replenishment is performed in a large amount, and in this case, if the Ni ore sand is segregated and exceeds 10%, the development of the mold strength may be hindered.

発明が解決しようとする手段Means to be Solved by the Invention

以上、これまで述べた課題を解決する方法として、鋭意研究の結果、Ｎｉ鉱滓砂を予め酸処理することにより、Ｎｉ鉱滓砂の混合割合が増加しても、フラン樹脂の硬化阻害が改善されることを見いだした。 As described above, as a method for solving the problems described so far, as a result of earnest research, even if the mixing ratio of Ni ore sand is increased, the inhibition of furan resin hardening is improved by pre-acid treatment of Ni ore sand. I found out.

酸処理する酸としては、硫酸、リン酸等の無機酸等があるが、いずれもそれぞれＳや吸湿の問題と再生砂への残存が考えられるため環境、鋳物品質のため好ましくない。 Acids to be acid-treated include inorganic acids such as sulfuric acid and phosphoric acid. However, any of them is not preferable because of the environment and casting quality because of problems of S and moisture absorption and remaining in reclaimed sand.

一方、有機酸として、スルホン酸、酢酸、蓚酸、等があるが、臭気等の面で作業環境の面で課題がある。その他有機酸ではコスト、環境、鋳物品質の面でクエン酸が最も好ましい。 On the other hand, there are sulfonic acid, acetic acid, succinic acid, etc. as organic acids, but there are problems in terms of working environment in terms of odor. Among other organic acids, citric acid is most preferable in terms of cost, environment, and casting quality.

クエン酸はアルコール、水によく溶ける一方約１２０℃で溶解して液状になる性質があるため、Ｎｉ鉱滓砂へのコーティングは常温、熱間何れの方法でも可能である。 Since citric acid dissolves well in alcohol and water, it has the property of dissolving at about 120 ° C. to become a liquid, and therefore, coating on Ni ore sand can be performed at any temperature or hot.

また、クエン酸はＮやＳを含有していないため、環境、鋳物品質の面で他の酸より優れている。 Moreover, since citric acid does not contain N or S, it is superior to other acids in terms of environment and casting quality.

本発明の混合骨材は主に珪砂と酸処理されたＮｉ鉱滓砂の混合物で構成される。珪砂の粒度としては旧ＪＩＳ５号〜６号で構成されており、Ｎｉ鉱滓砂の粒度は通常単独では鋳物砂として適用出来ない旧ＪＩＳ１号〜３号で構成される。表１に代表的な粒度分布を示す。 The mixed aggregate of the present invention is mainly composed of a mixture of silica sand and acid-treated Ni ore sand. The grain size of silica sand is composed of old JIS Nos. 5 to 6, and the grain size of Ni ore sand is usually composed of old JIS Nos. 1 to 3 which cannot be applied as casting sand alone. Table 1 shows a typical particle size distribution.

本発明のＮｉ鉱滓砂の酸処理には、クエン酸を用い、クエン酸の５０％アルコール溶液を製造し、キッチンミキサーを用いてＮｉ鉱滓砂１００部に対して重量比でクエン酸の５０％アルコール液２部を添加して混練し熱風を当てながら乾燥させてクエン酸でコーティングされたＮｉ鉱滓砂を製造した。 In the acid treatment of Ni ore sand of the present invention, citric acid is used to produce a 50% alcohol solution of citric acid, and using a kitchen mixer, 50% alcohol of citric acid in a weight ratio to 100 parts of Ni ore sand 2 parts of the liquid was added and kneaded, and dried with hot air applied to produce Ni ore sand coated with citric acid.

本発明によるクエン酸でコーティングされたＮｉ鉱滓砂と国産珪砂を表１に示す配合にて鋳型の強度強度試験を実施した。フラン樹脂１％と硬化剤０．４％を砂に添加してミキサーで混練した後標準テストピースを造型し、各経過時間毎の圧縮強度を測定した。その結果を表２に示す。 The strength and strength test of the mold was carried out with the composition shown in Table 1 of Ni ore sand coated with citric acid according to the present invention and domestic quartz sand. After adding 1% furan resin and 0.4% curing agent to sand and kneading with a mixer, a standard test piece was formed, and the compressive strength at each elapsed time was measured. The results are shown in Table 2.

発明の効果The invention's effect

予め酸処理したＮｉ鉱滓砂を珪砂に混合して使用することにより、次のような効果がある。
（１）酸処理されたＮｉ鉱滓砂をフラン自硬性法における焼着防止用のＮｉ混合砂として用いることにより、従来と殆ど変わらない強度発現が得れれる。
（２）酸処理されたＮｉ鉱滓砂と珪砂の混合砂はクロマイト砂等の焼着防止砂の代替えとして使用でき、硬化挙動も従来の珪砂と略同様の挙動を示す。
（３）酸処理されたＮｉ鉱滓砂と珪砂の混合砂をフラン自硬性クローズド法において補給砂としてバラシ場に大量に投入してもＮｉ鉱滓砂の著しい偏析が起きないため、安定した再生砂の硬化挙動が得られる。The following effects can be obtained by mixing and using previously treated nickel ore sand with silica sand.
(1) By using acid-treated Ni ore sand as Ni-mixed sand for preventing seizure in the furan self-hardening method, it is possible to obtain strength development that is almost the same as in the past.
(2) Mixed sand of acid-treated Ni ore sand and silica sand can be used as a substitute for anti-seizure sand such as chromite sand, and the hardening behavior is substantially the same as that of conventional silica sand.
(3) Even if a large amount of acid-treated Ni ore sand and silica sand is added as a supplementary sand in the furan self-hardened closed method to the ballast, no significant segregation of Ni ore sand will occur. Curing behavior is obtained.

Claims

フラン自硬性法において使用される耐火物混合物であって、Ｎｉ精錬時に発生する、２ＭｇＯ・ＳｉＯ_２を主成分とする熔融スラグが風砕により製造された耐火物で、粒径が０．０８〜３．５０ｍｍの範囲にあり、ＡＦＳ粒度指数が８〜３５の範囲で構成され、かつ表面か有機酸で処理された粗目の球状耐火物が、予め珪砂に重量割合で１０〜７０％混合され、そのまま鋳型の造型に適用できるように配合されていることを特徴とする焼着防止用混合砂。A refractory mixture used in the furan self-hardening method, which is a refractory produced by air crushing of molten slag mainly composed of 2MgO.SiO ₂ generated during Ni refining. 3. A coarse spherical refractory having a range of 50 mm, an AFS particle size index of 8 to 35, and a surface or treated with an organic acid, is previously mixed with silica sand by 10 to 70% by weight, A mixed sand for preventing seizure, which is blended so that it can be directly applied to mold making.

フラン自硬性法における使用砂の回収、再生、再使用を繰り返すクローズド法において、補給砂として用いられる請求項１に記載された混合砂。The mixed sand according to claim 1, wherein the mixed sand is used as supplementary sand in a closed method in which collection, regeneration, and reuse of used sand in the furan self-hardening method are repeated.