JPS5835735B2 - Anti-caking agent for granulated slag - Google Patents

Description

[Detailed description of the invention] The present invention relates to an anti-caking agent for granulated slag.

In recent years, with the depletion of natural sand resources, granular material obtained by crushing molten slag from steelmaking furnaces with water has been used as aggregate for concrete, aggregate for asphalt, and as a ground improvement material. Widely used.

Generally, granulated slag is made by crushing molten slag with high-speed water and granulating it, but especially when used as fine aggregate for concrete,
The slag is then passed through a sieving machine to improve its shape into spherical granules (referred to as processed granulated slag) before being shipped.

Therefore, it is desirable that the granulated slag or processed granulated slag have properties similar to natural sand in order to develop and expand the use and demand for the above-mentioned various civil engineering aggregates.

For this reason, JP-A-54-51993, JP-A-54-964
93 and Japanese Patent Application Laid-open No. 54-96494, in the pulverization step, air is blown into the molten slag or a specific chemical is mixed with the jet water and added to produce a dense, high-quality material with a high apparent specific gravity. It is proposed that granulated slag can be obtained.

However, these slags are produced in steel plants, etc. in quantities of several tens of tons.
When large amounts, such as several hundred tons, are piled up in the open, consolidation phenomena often occur due to the influence of natural weather under these unusual physical conditions.

This phenomenon is often seen in processed granulated slag, and once it solidifies, it becomes unusable or the amount of usage is limited, so it is imperative for the engineers concerned to solve this problem as soon as possible. It's becoming a problem.

The above-mentioned patent publications state that the granulated slag obtained by blowing air or adding specific chemicals in the granulation process has properties that can prevent caking while maintaining quality. According to what the present inventors know about the actual state of granulated slag, even high-quality spherical fine particles obtained through a well-controlled granulation process tend to solidify, especially in summer. The current situation is that caking occurs unless preventive measures are taken.

JP-A-54-112304 proposes a method in which carbon dioxide gas is brought into contact with the processed granulated slag in order to prevent it from solidifying.

Under these circumstances, the present inventors investigated the caking phenomenon of granulated slag and found that the cause of caking was mainly due to calcium oxide and silica, which are the main components of granulated slag, being dissolved in water in a moist state. It was confirmed that this occurs by elution into calcium hydroxide, etc., which are precipitated in a connected state between particles of granulated slag, and then solidified.

Based on this fact, we selected various agents that can prevent the precipitation of components such as calcium hydroxide in water under the conditions of granulated slag deposition, and as a result of intensive experimental studies, we found that:
The present invention has been completed to achieve extremely favorable results for the above objects.

According to the present invention, there is provided an anti-caking agent for granulated slag made of ligninsulfonic acid or a salt thereof, and a homopolymer of an aliphatic unsaturated carboxylic acid or a salt thereof that can be further copolymerized with ligninsulfonic acid or a salt thereof. A granulated slag anti-caking agent is provided which comprises a copolymer or a copolymer with other copolymerizable compounds.

The anti-caking agent of the present invention is particularly effective for processed granulated slag, but is of course also effective for ordinary granulated slag.

In the following, in the present invention, unless specifically referred to as processed granulated slag, the term granulated slag is used to include ordinary granulated slag and processed granulated slag.

The anti-caking agent for the granulated slag of the present invention uses geninsulfonic acid or its salts (for example, sodium, potassium, ammonium, etc. salts) as an essential active ingredient, but these do not need to be pure products.

In particular, the present invention utilizes waste materials, and it is desirable to use materials that are economically inexpensive.

From this point of view, it is possible to use a so-called sulfite pulp effluent composition, which is obtained by purifying and chemically treating the sulfite pulp effluent, which is a by-product when wood is digested by the sulfite method and produced as a by-product, as a raw material.

In other words, the sulfite pulp effluent composition includes everything from the above-mentioned by-product effluent except free sulfurous acid, which is almost the same as the pulp effluent itself, to those subjected to various advanced chemical treatments, and more than 50% of it is It contains ligninsulfonic acid or its salt as a main component, and is a substance that has an affinity for liquid or solid water.

These ligninsulfonic acids or salts thereof are preferably used as they are or as an aqueous solution of an appropriate concentration in order to uniformly coat the surface of the granulated slag.

The amount of the lignin sulfonic acid or its salt to be added is at least 0,00 weight φ, particularly preferably 0.03 weight plate, based on the granulated slag.

Using too much is not desirable from an economical and sometimes effective standpoint.

Furthermore, the anti-caking agent for granulated slag of the present invention includes a homopolymer or copolymer of an aliphatic unsaturated carboxylic acid or a salt thereof that can be further copolymerized with ligninsulfonic acid or a salt thereof, or other copolymerizable compounds. A copolymer with is added.

Addition of these polymers is effective in maintaining the anti-caking effect, and even higher anti-caking effects can be expected.

Representative examples of copolymerizable aliphatic unsaturated carboxylic acids include acrylic acid and methacrylic acid.

It may also be maleic acid.

Examples of these salts include alkali metal salts and ammonium salts.

Typical examples of other copolymerizable compounds include methyl acrylate, ethyl acrylate, acrylonitrile, acrylamide, and styrene.

These polymers usually have a molecular weight of 20,000 or less and are preferably water-soluble.

The amount used is 10=1-221, preferably 7:1-3:
1, the amount added is 0.01 weight φ or less, preferably 0.03 weight φ, based on the granulated slag.

In order to ensure the anti-caking effect of the granulated slag, the above addition amount should be adjusted depending on the use of the granulated slag, the properties of the granulated slag, the degree of caking caused by the storage environment, and the required storage period. The selection is determined by the merits and demerits.

In particular, when storage for more than one month is planned or when the granulated slag is intended for uses that require high quality, such as fine aggregate for ready-mixed concrete, the amount added within the above preferred range should be applied. Even if the amount added is increased to, for example, 0.1 weight φ or more, it is not possible to expect a particularly significant effect compared to the case of adding a preferable effective amount. There is a concern that the strength will be affected.

The granulated slag anti-caking agent of the present invention is extremely effective in achieving the purpose of preventing granulated slag from caking.

That is, the granulated slag anti-caking agent provided in the present invention can also bring about a corresponding effect when added to the circulating water used when crushing molten slag from a furnace with high-speed water. However, for the purpose of using chemicals more effectively and economically, the crystalline granulated slag obtained by pulverizing the molten slag from the furnace is shaped into fine spherical particles, and processed and granulated. It is also possible to add an anti-caking agent as a 1-3% aqueous solution to the processed granulated slag during the processing step or thereafter.

ε Thus, by using the anti-caking agent of the present invention, it was possible to prevent granulated slag that was piled up and stored outdoors from caking.

Particularly in the past, during high temperatures in summer, solidification occurred within a few days to a week at most, which caused various problems in terms of on-site technology, management of commercial products, and economics, but with the present invention, work can be done even under harsh conditions. This makes it possible to maintain properties for more than two months and maintain quality suitable for various uses, and its industrial effects are extremely significant.

EXAMPLES Hereinafter, the effects of the present invention will be illustrated by giving experimental examples and examples, but the present invention is not limited thereto.

Experimental example 1 Bulk specific gravity made from blast furnace slag from our steelworks: 2.684
, fine aggregate with water absorption rate of 0.857%, water content of 5.7%, and particle size distribution shown in Table 1 (refers to fine aggregate used for asphalt or ready-mixed concrete, etc., and fine aggregate used for roadbed improvement, etc.). Processed granulated slag (for coarse aggregate) was used as a sample, and 16 samples of 20 pieces each were collected from an on-site storage site using the four-part method.

For each of these 15 samples, a predetermined amount of anti-caking agent was uniformly sprinkled on the processed granulated slag, and the mixture was left in a simple constant temperature and humidity device at a temperature of 25-50°C and a humidity of 60-90°C. Thereafter, samples were collected by dividing into four at each oral time point of 1 week, 20 days, 40 days, and 60 days, and the particle size distribution was measured.

The measurement method was based on JIS standard A1102.

The particle size distribution here indicates that a caking state has appeared when the particle size distribution is on the coarse side of the nominal size of the sieve compared to the original sample, which means that the caking effect of the drug is low.

Table 2 shows the results of each experiment including experiments in which no drug was added.

Example 1 In the process of crushing the molten slag with high-speed water and passing the obtained granulated slag through a sieving machine to make processed granulated slag, approximately 2% aqueous solution of each drug was added to 1 ton of granulated slag. It was added and stirred at a ratio of .

The coarse particle ratio of the above-mentioned processed granulated slag was 2.22, and the particle size distribution was as shown in Table 3.

We created four piles of about 1 m high each containing approximately 10 tons of processed granulated slag, and measured the solidification status of the processed granulated slag piles for two months after the piles were piled up by sampling and inserting sticks from various parts of the piles. We investigated.

During this time, the outside temperature near the mountain was at least 22°C139°C1
The average temperature was about 33°C.

The results are shown in Table 4 along with those without additives.

the best

Claims (1)

[Scope of Claims] 1. A granulated slag anti-caking agent containing ligninsulfonic acid or its salt as an active ingredient. 2. The granulated slag anti-caking agent according to claim 1, wherein the ligninsulfonic acid or its salt is a sulfite valve drainage composition. 3. A granulated water granulate comprising lignin sulfonic acid or its salt and a homopolymer or copolymer of a copolymerizable aliphatic unsaturated carboxylic acid or its salt, or a copolymer with other copolymerizable compounds as an active ingredient. Anti-caking agent for slag. 4. The granulated slag anti-caking agent according to claim 3, wherein the ligninsulfonic acid compound is a sulfite pulp waste liquid composition. 5. The anti-caking agent for granulated slag according to claim 3, wherein the copolymerizable aliphatic unsaturated carboxylic acid is acrylic acid, methacrylic acid or maleic acid. 6 A copolymer of a copolymerizable aliphatic unsaturated carboxylic acid or its salt and another copolymerizable compound is acrylic acid,
The anti-caking agent for granulated slag according to claim 3, which is a copolymer of methacrylic acid or a salt thereof and methyl acrylate, ethyl acrylate, acrylonitrile, acrylamide or styrene.