JP4590864B2 - Grinding method - Google Patents

Description

The present invention relates to a pulverization method, and more particularly, to a pulverization method for inorganic materials, and more particularly to a pulverization method that enables pulverization of a material that easily adheres to a pulverizer to eliminate or reduce trouble caused by adhesion.

For example, when limestone CaO ₃ obtained by firing limestone CaCO ₃ is pulverized to obtain powdered lime, powder produced by pulverization tends to adhere to the pulverizer. As a result, the efficiency of pulverization may decrease and the desired particle size may not be reached. An adhesion inhibitor such as stearic acid, silicone oil, propylene glycol or dipropylene glycol is used to suppress the adhesion of the material to be crushed to such a pulverizer and to enable smooth pulverization. Has been. This kind of adhesion inhibitor is useful as far as pulverization is concerned, and adhesion can be effectively prevented by adding several percent by weight to the material to be crushed.

However, when a powder pulverized using a known adhesion inhibitor, such as the above-mentioned quicklime powder, is pressed and formed into pellets or briquettes, the resulting molded body has low strength and is suitable for normal handling and transportation. Often unbearable. This tendency is observed when a material to be crushed with high adhesion and a material to be pulverized with little or no adhesion are mixed and pulverized, and the latter is relatively large and the former adhesion is diluted. Even in quantitative ratios that can be expected to weaken, it is still noticeable. For example, in order to produce pellets of a mixture of quicklime and iron ore that are put into a converter as a steelmaking raw material (by weight, 40% quicklime + 60% iron ore), when mixing and grinding limestone and iron ore powder, There is a problem of adhesion as described above. Therefore, there has been a demand for a measure for preventing the material to be crushed from adhering to the pulverizing apparatus during pulverization without reducing the strength of the powder molded body.

On the other hand, with the recent development and popularization of OA equipment, solid powder toner has been frequently used as ink in copying machines, facsimiles, and printers. As a result, a large amount of waste is handled as waste toner. Since both the toner and the waste toner are compositions composed of a thermoplastic synthetic resin and a colorant that are relatively easily melted, it has been considered in various technical fields to use the composition as a binder.

To give some specific examples, first, in the field of steelmaking and steelmaking, powder dust containing heavy metals and waste toner are mixed, and then compression molded into pellets are put into a metal melting furnace. Thus, there is one that collects metal and makes a binder useful as a fuel (Patent Document 1). It is the same flow that iron-containing dusts are combined with waste toner, are made into particles, and are used as a raw material for iron making (Patent Document 2). There are also proposals to use waste toner to produce a flux for steel making from aluminum soot or aluminum ash (Patent Documents 3 and 4).
JP 2000-070900 A JP 2003-147446 A JP 2002-018412 A JP 2003-138320 A

It has been proposed that waste toner is added to fly ash generated in a thermal power plant and granulated into pellets, which can be used to keep hot metal warm and adjust the components of molten slag, or to use combustion heat as a heat source (Patent Literature) 5). There is also a technique in which waste toner is added and kneaded in the production of coal molding composed of pulverized coal and a tar binder (Patent Document 6).
JP2002-097514 JP 2003-119469 A

The inventors have conceived and tried to use the waste toner used as a binder in this way for manufacturing a green compact from quicklime, and the effect was obtained. Therefore, an attempt was made to omit the process by adding waste toner to quicklime that is compacted after pulverization and adding the waste toner prior to pulverization and mixing the lime simultaneously with the pulverization. As a result of the experiment, surprisingly, the presence of waste toner significantly reduces the adhesion of powder to the pulverizer and, in exchange, the effect of the waste toner as a binder is almost lost. Some have found that it works rather negatively. However, it was also found that the waste toner added before pulverization and transferred to the subsequent molding step does not substantially hinder the compacting, although it is negative.

Therefore, the object of the present invention is to utilize the above knowledge obtained by the inventors, and even if a material that easily adheres to a pulverizer during pulverization is targeted, adhesion is remarkably reduced, and thus pulverization efficiency is reduced. without and to provide desired over Ru readily der to reach the particle size, the grinding method where Ru can be obtained product powder suitable for compression molding.

In the pulverization method of the present invention that achieves the above object, when pulverizing quicklime or a mixture of quicklime and other materials, 0.1 to 10 parts by weight of waste toner is added to 100 parts by weight of the material to be pulverized. By pulverizing, the powder is prevented from adhering to the pulverizer and hindering the pulverization, and the pulverization is advanced, and a product powder suitable for pressure molding is obtained.

When using the pulverization method of the present invention, graphitic carbon contained as a colorant in the waste toner adheres to the surface of the apparatus and the surface of the pulverization medium such as a ball or rod, and covers the surface. As a result of acting like a lubricant or a release agent, it is understood that adhesion of the powder to the pulverizer is suppressed. Thus, in the pulverization method of the present invention, the pulverization efficiency is not substantially reduced due to adhesion, and it is easy to reach a desired particle size. Although the waste toner remains in the powder obtained by pulverization, it is not a hindrance to compaction molding, which is a subsequent process in many cases. Therefore, the pulverization method of the present invention is a product. As long as the waste toner may remain in the powder, it is applicable to pulverization of a material to be crushed having a wide and strong adhesion.

The crushed material having high adhesion is typified by the above-mentioned quick lime, and the mixture of quick lime and other materials, for example, the mixture of the above-mentioned quick lime-iron ore powder is also applied to the pulverizer as described above. Although the problem of adhesion is included, the pulverization method of the present invention can be preferably carried out also for them.

The pulverization apparatus useful for pulverizing with the addition of waste toner according to the present invention covers most apparatuses in practical use. Among them, such as a vibration mill, a ball mill, and a rod mill, with respect to an apparatus having a mechanism in which a material to be pulverized is impacted between an apparatus wall and a pulverizing medium or between pulverizing media. The present invention is particularly effective.

The amount of waste toner added to the material to be pulverized varies depending on the ease of adhesion of the material, but in many cases, the addition of 0.1% or more by weight will have an effect of suppressing adhesion. I can't. It is preferably 1% or more, particularly 3-5% with respect to quicklime. This effect is saturated even if the amount added is increased, and in many cases the significance is lost even if the amount exceeds 10%.

A mixture of materials to be crushed containing 40 parts by weight of quicklime and 60 parts by weight of iron ore was pulverized by a vibration mill. In the pulverization, various adhesion inhibitors shown in Table 1 were similarly added at the ratios shown in Table 2 (wt% of the external number based on the material to be crushed). After the grinding operation for 60 seconds, the inside of the vibration mill was examined, and the degree of adhesion of the powder was evaluated in the following five stages.
0: Substantially not attached 1: Adhered a little, but fell off when touched 2: Adhered to some extent 3: Adhered, but could be scraped off with a spoon 4: Adhered firmly, could not be scraped off with a spoon

Each of the obtained powders was put into a mold and pressed to form a tablet having a diameter of 40 mm and a thickness of 7 mm by applying a pressure of 9.8 × 10 ⁷ Pa. About this molded object, the intensity | strength (bending fracture load) was measured using the Kiyama-type hardness meter, and the influence which the adhesion inhibitor has on the moldability of powder was investigated. The results are also shown in Table 1. From the results in Table 1, the following matters are concluded.
-As for the known adhesion inhibitor, the degree of adhesion of the powder to the pulverizer becomes lower as the blending ratio is increased, but the strength of the green compact is lowered to an unsuitable level for handling.
In the case of the present invention in which waste toner is used as an adhesion inhibitor, the effect of suppressing the adhesion of powder is obtained, and the strength of the green compact is well maintained, which is close to the case without an adhesion inhibitor. Even if it is added in a large amount, the moldability is rather improved without decreasing.

A mixture having the same composition as that crushed in Example 1 and 3% by weight of waste toner added thereto was pulverized using a ball mill. For comparison, those without added waste toner were also crushed. After milling for 60 minutes, open the mill to collect the contents, examine the state of the powder adhering to the ball, and calculate how much adheres to the entire grinder (container and ball) using the following formula: did. Adhesion rate = (charging amount−recovery amount) / charging amount × 100 (%)

Also in this case, as in Example 1, molding into a tablet and measurement of its breaking load were performed. The values are shown in Table 2 together with the adhesion rate.

Claims (2)

In pulverizing quicklime or a mixture of quicklime and other materials, 0.1 to 10 parts by weight of waste toner is added and pulverized to 100 parts by weight of the material to be pulverized, so that the powder adheres to the pulverizer. A pulverization method characterized in that the pulverization proceeds while suppressing the hindering of pulverization and a product powder suitable for pressure molding is obtained. The pulverization method according to claim 1, wherein the pulverization apparatus is a vibration mill, a ball mill or a rod mill.