JPS6114117B2 - - Google Patents

Description

[Detailed description of the invention]

Phosphoric acid catalysts are industrially important for various process operations in the organic chemical industry, such as polymerization, isomerization, alkylation, dehydration, and hydration reactions. This material is discharged as so-called phosphoric acid waste catalysts (hereinafter simply referred to as waste catalysts) after operation for a specified life period, but a considerable amount of this material is discarded without adequate recovery and utilization, or is disposed of in factories. Coupled with trends in resource conservation and environmental pollution prevention, there is a strong desire for an effective way to recycle these resources. As a method for recycling the waste catalyst, the present inventors have focused on using it as a raw material for producing superphosphate lime, which can effectively utilize not only the phosphorus content but also the silicic acid content as a carrier component, and have developed an industrial treatment method for using it. After conducting various studies on the method, we found that there were the following problems. In other words, spent catalyst is made into pellets by adhering phosphoric acid to a carrier, but it is highly hygroscopic and difficult to handle in conveyors, crushers, etc., and can easily cause corrosion of equipment.When mixed with phosphate rock and crushed, it generates fluorine-containing gas and Industrially, it is accompanied by the generation of acidic dust, and some or most of the phosphoric acid content of the waste catalyst becomes pyrophosphoric acid during use as a catalyst, and the reactivity with phosphate rock is not necessarily good. Implementation issues remain. As a result of further studies, the inventors of the present invention found that all of the above problems could be avoided by pre-treating the waste catalyst under specific conditions and then turning it into fertilizer. It has been reached. The present invention includes a first step in which a solid alkali is added to a phosphoric acid-based waste catalyst to neutralize the phosphoric acid content to a primary phosphate to a tertiary phosphate, and a ratio of the spent catalyst/phosphate rock is approximately A second step of mixing the neutralized product and phosphate rock in a ratio not exceeding 30/70, pulverizing the mixture, and reacting with sulfuric acid to form superphosphate lime. This is the manufacturing method. As mentioned above, the phosphoric acid catalyst is made by adsorbing orthophosphoric acid onto a carrier, usually a clay mineral such as diatomaceous earth, and pelletizing it into a cylindrical shape with a diameter of about 5 mm and a length of about 1 cm. During use, phosphoric acid may be converted to pyrophosphoric acid, or a small amount of treated organic matter may be included. The pellets taken out as waste catalysts are often broken down and some of them are powdered, but they are used as they are in the present invention. Examples of the solid alkali added in the first step include slaked lime, quicklime, limestone, magnesium hydroxide, and fused phosphorous fertilizer, but it is most appropriate to use a calcium-based alkali, especially slaked lime. The amount added is the amount that converts the phosphoric acid content in the spent catalyst into primary or tertiary phosphate, preferably primary or secondary phosphate. Since pyrophosphoric acid is converted to the ortho form by the process of the present invention, the required amount of solid alkali can be easily determined. The neutralization treatment is carried out by mixing a predetermined waste catalyst and a solid alkali and, if necessary, pulverizing the mixture. If the amount of solid alkali is small or the neutralization reaction does not proceed sufficiently, it may absorb moisture during mixing and pulverization for neutralization, making it difficult to process, generating acidic dust, or causing problems in the next process. Fluorine-containing gas may be generated during mixing with phosphate ore and crushing. If the amount of solid alkali is too large, the quality of the product will deteriorate and the solid alkali and sulfuric acid in the next process will be consumed excessively, which is not desirable. In the second step, the neutralized product and phosphate rock are mixed and used in such a ratio that the ratio of spent catalyst/phosphate rock does not exceed about 30/70. If a large amount of waste catalyst is used in excess of the above ratio, the manufacturing conditions and product will be different from those in the case of manufacturing superphosphate lime from normal phosphate rock, and the small amount of organic matter contained in the waste catalyst will become a product. Although consideration must be given to the mixing of Next, details of the present invention will be explained using experimental examples.
The used catalyst was pellets made of diatomaceous earth used in the alkylation process for producing Qyumen, and the particle size was +2 mm 64% and -2 mm 36% due to disintegration, and the analytical values were P ₂ O ₅ 51.83% and moisture content. It was 9.1%. In the first step, slaked lime is mixed with this material as a solid alkali, and pulverized (using a hammer mill, -20
I did it. In the second step, the obtained neutralized product and phosphate rock (P ₂ O ₅ 31.63%) are mixed and crushed (using a Raymond mill), and the crushed product is mixed with 70% sulfuric acid according to the usual method for producing lime superphosphate. I reacted. The conditions and results of the experiment were as follows.

[Table] As is clear from the above results, by mixing a predetermined amount of waste catalyst and solid alkali according to the present invention, pellets can be crushed very easily without causing corrosion of the equipment. In addition, when mixing the obtained neutralized product in a predetermined amount with phosphate ore and pulverizing it, and acid decomposing this pulverized product with sulfuric acid, there are concerns such as generation of fluorine-containing exhaust gas and equipment corrosion during the pulverization process. The problem can be avoided. In addition, the properties and fertilizing properties of the superphosphate lime obtained in No. 3 and No. 4 within the scope of the present invention are as good as those of conventional superphosphate lime, and the method of the present invention can remove waste catalyst. It can be seen that it is extremely advantageous industrially for recycling. Example 1 52 parts of waste catalyst (P ₂ O ₅ 51.83%) in anhydrous equivalent and 26 parts of slaked lime were mixed, ground in a hammer mill, and neutralized. This stuff contains phosphate rock (P ₂ O ₅ 31.63%, F3.79
%) were mixed and dry ground in a Raymond mill. At this time, no troubles such as generation of fluorine-containing gas, equipment corrosion, generation of acidic dust, etc. occurred.
Next, 574 parts of this finely pulverized material and 463 parts of sulfuric acid having a concentration of 70% were reacted in a lime superphosphate manufacturing apparatus and subjected to estimated aging to obtain 1000 parts of lime superphosphate containing 17.8% soluble phosphoric acid. Example 2 Anhydrous equivalent amount of 77 parts of waste catalyst (P ₂ O ₅ 51.83%),
20 parts of slaked lime and 20 parts of limestone were mixed and neutralized by crushing in a hammer mill. This was mixed with 470 parts of phosphate rock (P ₂ O ₅ 31.63%, F3.79%) and dry-pulverized in a Raymond mill. At this time, no troubles such as generation of fluorine-containing gas, equipment corrosion, generation of acidic dust, etc. occurred. Next, 604 parts of this finely pulverized material was reacted with 439 parts of sulfuric acid having a concentration of 70% in a lime superphosphate manufacturing apparatus, and the mixture was subjected to estimated ripening to obtain 1000 parts of lime superphosphate containing 18.3% soluble phosphoric acid. Example 3 138 parts of waste catalyst (P ₂ O ₅ 51.83%) in anhydrous equivalent and 74 parts of slaked lime were mixed and neutralized by pulverization in a hammer mill. This stuff contains phosphate rock (P ₂ O ₅ 31.63%, F3.79
%) were mixed and dry ground in a Raymond mill. At this time, no troubles such as generation of fluorine-containing gas, equipment corrosion, generation of acidic dust, etc. occurred.
Next, 626 parts of this finely pulverized material was reacted with 459 parts of sulfuric acid having a concentration of 70% in a lime superphosphate manufacturing apparatus, and the mixture was subjected to estimated ripening to obtain 1000 parts of lime superphosphate containing 19.5% soluble phosphoric acid.

Claims (1)

[Claims] 1 A first step of neutralizing the phosphoric acid-based waste catalyst by adding a solid alkali so that the phosphoric acid content becomes primary or tertiary phosphate, and the ratio of the spent catalyst/phosphate rock being approximately
A second step of mixing the neutralized product and phosphate rock in a ratio not exceeding 30/70, pulverizing the mixture, and reacting with sulfuric acid to produce superphosphate lime. Production method.