WO2017063580A1

WO2017063580A1 - Ceramsite sand for casting

Info

Publication number: WO2017063580A1
Application number: PCT/CN2016/102107
Authority: WO
Inventors: 祝建勋; 赵国庆
Original assignee: 济南圣泉倍进陶瓷过滤器有限公司
Priority date: 2015-10-15
Filing date: 2016-10-14
Publication date: 2017-04-20
Also published as: CN105344919A

Abstract

A ceramsite sand for casting and a manufacturing method therefor. The ceramsite sand is obtained by mixing, granulating and sintering a refractory material. Taking the weight of the ceramsite sand as 100 wt%, the ceramsite sand includes more than 55 wt% of silicon dioxide, 25~45 wt% of aluminium oxide, and remaining other substances, the remaining other substances being 0.5 wt% ~ 10 wt% of one or more of potassium oxide, lithium oxide, magnesium oxide and boron oxide. The ceramsite sand for casting has low resource and energy consumption, and does not cause sand adhesion.

Description

Ceramsite sand for casting

The present application claims priority to Chinese Patent Application No. 201510665886.6 (the title of which is a ceramsite for casting, filed on October 15, 2015), the entire disclosure of which is hereby incorporated by reference.

Technical field

The invention relates to the field of casting materials, in particular to a cast ceramsite sand.

Background technique

Ceramsite sand, also known as orb sand, is a high-grade alternative to quartz sand. Ceramsite sand has been widely concerned because it can overcome the shortcomings of large expansion coefficient of quartz sand, low precision of castings, serious surface sanding and difficulty in clearing sand, and greatly improve the quality of castings.

At present, the ceramsite sand for casting is mainly made of high-alumina ore. There are mainly two preparation methods. One is to melt the raw materials at a high temperature, to form particles by spray atomization, and to obtain various sizes of ceramsite sand after sieving. The other is obtained by mechanical granulation, sintering, and sieving to obtain ceramsite sand.

CN 1899722A discloses a novel artificial foundry sand and a preparation method thereof, wherein the artificial foundry sand is made of bauxite ore with a content of 45-90% of aluminum oxide as a raw material, and after being electrofused into a liquid state, after 70-85 m/s. The air pressure is used to crush and cool the liquid raw material by strong wind, and then a spherical or spheroidal shaped sand is obtained, which is sieved to obtain an artificial ceramsite sand.

CN104030708A discloses a sand for precision casting and a preparation method thereof, wherein the sand for precision casting is mixed with bauxite 79-95%, clay 3-20%, manganese ore 0.5-5%, and hematite 0.2-1%. , obtained by granulation, drying and sintering.

CN103212665A discloses an artificial ceramsite sand comprising 70%-85% by mass of Al ₂ O ₃ , 8%-12% silicon, 2% Fe ₂ O ₃ , and the balance being impurities.

Although the existing ceramsite sand can overcome the shortcomings of quartz sand and improve the quality of castings, it generally uses bauxite with higher content of alumina as the main raw material, and the production process mostly uses electrofusion or high temperature kiln. In the way of furnace sintering, there is a problem that the high-quality high-aluminum ore resource consumption is large and the energy consumption is high.

In addition, it is generally believed that if the amount of aluminum oxide in the ceramsite sand is lowered, it will result in sticking sand. Viscous sand is a kind of casting surface defect, which is an adhesive layer of metal and sand formed on the surface of the casting.

Summary of the invention

The technical object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a ceramsite sand for casting which has low resource and energy consumption and does not cause sticking sand.

The invention includes:

A ceramsite sand for casting, which is obtained by mixing, granulating, and sintering a refractory material, wherein the ceramsite sand contains 55 wt% or more based on 100 wt% of the ceramsite sand weight. Silica, 25 to 45 wt% of aluminum oxide, and the balance of other substances, the balance of other substances being 0.5 wt% to 10 wt% selected from the group consisting of potassium oxide, lithium oxide, magnesium oxide and boron oxide One or more.

2. The ceramsite sand according to item 1, wherein the ceramsite sand comprises 25 to 44% by weight of aluminum oxide.

3. The ceramsite sand according to item 1 or 2, wherein the ceramsite sand comprises 25 wt% to 40 wt% of alumina, and 55 wt% to 75 wt% of silica.

4. The ceramsite sand according to any one of items 1 to 3, wherein the ceramsite sand has a bulk density of 1.0 to 1.8 g/cm ³ .

5. The ceramsite sand according to any one of items 1 to 4, wherein the sintering temperature is from 1100 to 1200 °C.

The ceramsite sand according to any one of items 1 to 5, wherein the ceramsite sand has a refractoriness of less than 1600 °C.

The ceramsite sand according to any one of items 1 to 6, wherein the ceramsite sand has a refractoriness of not less than 1550 °C.

The ceramsite sand according to any one of items 1 to 7, wherein the aluminum oxide is derived from an aluminum ore having a low aluminum content.

The ceramsite sand according to any one of items 1 to 8, wherein the low aluminum content aluminum ore is selected from the group consisting of kaolin and coke gems.

A method of producing a casting, wherein the mold or core is produced by using the ceramsite sand for casting according to any one of claims 1 to 9.

11. The method of clause 10, wherein the casting has a casting temperature below 1600 °C.

12. A ceramsite sand for casting, wherein the ceramsite sand is obtained by mixing, granulating, and sintering a refractory material, wherein the ceramsite sand contains 90% by weight or more based on 100% by weight of the ceramsite sand Silica and other materials in the balance.

These other substances may be small amounts of impurities contained in the natural ore, or may be functional ingredients introduced to improve performance. The content of the other substance is usually not less than 0.5% and not more than 10%. The other substance may be one or more selected from the group consisting of potassium oxide, lithium oxide, magnesium oxide, and boron oxide.

The silica may have a weight content of not less than 90% by weight. It is generally believed that the higher the content of alumina, the higher the refractoriness; and the higher the silica content, the lower the refractoriness. However, the ceramsite sand can also be obtained by using a high-purity silica sand through a ball forming process. The inventors have found that the high silica content ceramsite sand of the present invention can also maintain a high degree of refractoriness, and at the same time has a low cost. It is not easy to produce defects, veins, burrs, and small dust when used. Preferably, the high silica content ceramsite sand may even be completely free of alumina.

The ceramsite sand for casting provided by the invention has a content of aluminum oxide which is obviously lower than that of the ceramsite sand used in the prior art, and can adopt aluminum-free or low-aluminum ore as a raw material, which greatly reduces the production cost and is reasonable. Use mineral resources. Secondly, by using aluminum-free or low-aluminum mineral as raw material, the semi-finished ceramsite sand of the invention can be prepared by sintering at a lower temperature, thereby saving energy. Moreover, it is surprising that the ceramsite sand of the invention, although having a low content of aluminum oxide, does not exhibit sticking.

The ceramsite sand provided by the invention has lower refractoriness than ordinary ceramsite sand, and is suitable for casting shapes with a casting temperature lower than 1600 °C. In addition, the casting ceramsite sand provided by the present invention can further reduce the thermal expansion coefficient of the ceramsite sand by introducing one or more of potassium oxide, lithium oxide and boron oxide (the thermal expansion coefficient at 1000 ° C ≤ 5×10 ^-6 /°C) to increase the strength of ceramsite sand.

The ceramsite sand provided by the invention has lower bulk density than ordinary ceramsite sand, and the bulk density can be between 1.0 and 1.8 g/cm ³ , and the heat capacity is small, and the local solidification is not easy to be too fast during the casting process, and can be a certain degree. Reduce casting defects.

detailed description

The embodiments of the present invention are described in detail below, but the present invention may be embodied in many different ways as defined and covered by the appended claims.

As indicated in the background of the present invention, in the prior art, ceramsite sand is generally used as a main raw material of bauxite having a higher content of alumina, and when the ceramsite is used for casting temperatures below 1600 ° C, For example, when castings of around 1000 ° C are produced, this causes technical problems of high aluminum mineral resources and energy waste.

In order to solve this technical problem, the inventors of the present invention provide a foundry ceramsite sand using aluminum-free or low-aluminum minerals as a raw material, the foundry ceramsite sand comprising silica, and the ceramsite sand The weight of the silica is 100% by weight, and the weight content of the silica is not less than 55 wt%. In the present invention, the content of the aluminum oxide in the ceramsite sand is not more than 45%, and may be, for example, any integer between 30 and 44% (for example, 31, 32, 33, 34, 35, 36, 37, 38) , 39, 40, 41, 42, 43%), may also be less than 30%; the content of aluminum oxide in the ceramsite sand is not less than 5%, more preferably not less than 15%, more preferably not less than 25 %. The strength and refractoriness of the ceramsite sand can be appropriately ensured because of the appropriate aluminum oxide content. In another aspect of the invention, the content of silica in the ceramsite sand may be not less than 90%.

In the present invention, the source of the aluminum oxide may be a low-aluminum content aluminum ore, such as kaolin, pyrometall, and the source of the silica may be low aluminum ore, silicon micropowder, silica sand, or the like. In the present specification, "aluminum ore having a low aluminum content" means an alumina content of ≤ 45%.

The ceramsite sand further includes one or more of potassium oxide, lithium oxide and boron oxide, and the weight of the potassium oxide, lithium oxide or boron oxide is 100% by weight of the ceramsite sand. The content is from 0.5% by weight to 10% by weight. In the present invention, the above-described ceramsite sand for casting can obtain a smaller coefficient of thermal expansion by introducing lithium oxide, potassium oxide or boron oxide. can provide The raw materials for these elements include potassium feldspar, alumite, nepheline, potassium-bearing sand shale, spodumene, lithium feldspar and lithium mica, borate ore and boric acid. These elements can also be introduced by other industrial synthetics, although it is not preferred from a cost perspective.

In a preferred embodiment of the present invention, the ceramsite sand comprises, by weight percent, 25 wt% to 40 wt% of alumina, 55 wt% to 75 wt% of silica, and 0.5 wt% to 10 wt%. One or more of potassium oxide, lithium oxide and boron oxide. Although only the above components are mentioned in the present invention, it is easy to understand that it is permissible to contain a small amount of other metal elements in the ceramsite sand, but in general, these other metal elements should not exceed 10%, preferably their oxides. The amount does not exceed 10%. These metal elements can be introduced in the form of oxides, silicates, borates, for example in the form of natural minerals.

The ceramsite sand for casting provided by the invention has a content of aluminum oxide which is obviously lower than that of the ceramsite sand used in the prior art, and can use aluminum-free or low-aluminum mineral as a raw material, which greatly reduces the production cost and is reasonable. Use mineral resources. Moreover, by using aluminum-free or low-aluminum mineral as a raw material, the semi-finished ceramsite sand of the present invention can be prepared by sintering at a lower temperature, thereby saving energy. The lower temperature may be, for example, 1100 to 1200 °C.

The method of preparing the ceramsite sand of the present invention generally includes the steps of batching, ball milling, granulating, sintering, and the like. The ingredients are crushed into pellets by various types of mine crushers. The particle size is preferably below 8mm, and then milled with a ball mill. After grinding, the slurry is sprayed and atomized by compressed air to form spherical particles. After drying and sintering.

Example

The technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the scope of protection of the present invention is not limited thereto.

The preparation method of the ceramsite sand used in the following examples: one or several of a block of low aluminum ore, potassium feldspar, spodumene, borax, a total of 200 kg, PVA 0.9 kg, water 60 kg added to the ball mill tank, Adding a grinding ball, ball milling for 5 hours, preparing a slurry, discharging and placing in a container;

b) the slurry is sprayed in a container, and is sprayed and atomized by compressed air having a pressure of 0.8 MPa, adjusted to a drying temperature of 200 ° C, and dried into spherical particles;

c) sieving with a standard sieve of 10 to 150 mesh to obtain semi-finished products of various mesh numbers;

d) The semi-finished product is sintered at 1200 ° C in an electric kiln to obtain finished products of various mesh numbers.

The following three comparative samples were purchased from the market.

The ceramsite sand for casting prepared by the above steps and the purchased sample were tested for their components by chemical titration. After examination, the ceramsite sand for casting prepared in the examples was classified as follows according to the weight percentage.

Table 1

Various parameters are tested with reference to the following standards or methods:

Bulk density: GB/T 21354-2008

1000 °C thermal expansion coefficient GB/T 7320-2008

Fire resistance GB/T 7322-2007

Sanding effect test: Add 1% furan resin to 5000g of various samples, mix well, and make sand type with cavity of 200*100*400mm, pour metal liquid of various temperatures into sand cavity, etc. After the liquid is cooled, a metal sample is formed, and after the sand type is broken, the surface sanding condition of the metal sample is observed.

The test results are shown in Table 2.

Table 2

It should also be noted that the ceramsite sands of Example 4 and Example 5 were tested, and no defects, veins, burrs, and dust were observed during use.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

A ceramsite sand for casting, wherein the ceramsite sand is obtained by mixing, granulating and sintering a refractory material, wherein the ceramsite sand contains 55 wt% or more based on 100 wt% of the ceramsite sand weight. Silica, 25 to 45 wt% of aluminum oxide and the balance of other substances, the balance of other substances being 0.5 wt% to 10 wt% of one selected from the group consisting of potassium oxide, lithium oxide, magnesium oxide and boron oxide Kind or more.
The ceramsite sand according to claim 1, wherein the ceramsite sand contains 25 to 44% by weight of aluminum oxide.
The ceramsite sand according to claim 1, wherein the ceramsite sand comprises 25 wt% to 40 wt% of alumina, and 55 wt% to 75 wt% of silica.
The ceramsite sand according to claim 1, wherein the ceramsite sand has a bulk density of 1.0 to 1.8 g/cm 3 .
The ceramsite sand according to claim 1, wherein the sintering temperature is from 1100 to 1200 °C.
The ceramsite sand according to claim 1, wherein the ceramsite sand has a degree of refractoriness of less than 1600 °C.
The ceramsite sand according to claim 1, wherein the ceramsite sand has a refractoriness of not less than 1550 °C.
The ceramsite sand according to claim 1, wherein the aluminum oxide is derived from an aluminum ore having a low aluminum content.
A method of producing a casting, wherein a casting mold or a core is produced by using the ceramsite sand for casting according to any one of claims 1 to 8.
The method of claim 9 wherein the casting has a casting temperature below 1600 °C.