JPS58104022A - Manufacture of crystallite synthetic anhydride - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing synthetic anhydrides in the form of microcrystals from a microcrystalline mixture consisting of flue gas desulfurization intermediates containing lucium dihydrate.

Anhydrides can be produced by one method. Depending on the production method, they are classified into natural anhydrides and synthetic anhydrides.◎Natural anhydrides can be produced by the following method.

a) Mining and processing of naturally produced anhydrous materials b) Heating dehydration of natural calcium sulfate dihydrate (gypsum) The anhydrous materials listed above based on the above method react slowly, so if they are used as they are, they cannot be used in the building materials industry. It can be used for
It must be further processed for use in the building materials industry. In this case, in addition to fine grinding, multiple additives (?I,
There is a fee to add reaction accelerator).

Km of synthetic anhydrides are produced during the production of hydrofluoric acid, as in Hatochi. This anhydride cannot be used in the building materials industry unless it is finely ground and added with additives to improve the reactivity. Synthetic anhydrides can also be prepared from chemical gypsum by a dry calcination operation. Furthermore, synthetic anhydrides can also be obtained from flue gas desulfurization products. In this case, the calcium sulfite-containing component and the absorbent residue are wet-oxidized to calcium sulfate dihydrate in a known manner, and this dihydrate is then subjected to a dehydration treatment.
11. ．． The natural anhydrides and synthetic anhydrides used in the Jiankui industry are further processed into D I N 42 in the cement industry.
It can be used as an anhydride binder specified in the 08K standard, or as a binder component for general-purpose building materials (e.g., bracing materials for breasts, and binders for supporting materials).

- Commonly known, in various processes (e.g. flue gas desulfurization process), an intermediate product containing calcium hemihydrate and calcium sulfate dihydrate, which can be used as a raw material for the production of synthetic anhydrides. Something comes into being.

It is therefore an object of the present invention to use flue gas desulfurization products containing calcium sulfite hemihydrate and calcium sulfate dihydrate and, with appropriate treatment, to manufacture building materials without the use of reactive additives. The object is to provide a method by which synthetic anhydrides can be prepared in a usable physical form.

To achieve this objective, according to the invention, a heat treatment is carried out in the temperature range of 200 to 900'C in the presence of 1 ljk, and the calcium sulfite raw wood salt-containing component in the flue gas desulfurization intermediate product is is first dehydrated to produce calcium sulfite, which is then oxidized to produce calcium sulfate, while dehydrating the calcium sulfate dihydrate-containing component in the intermediate product.

If an intermediate product of the wet flue gas desulphurization process is used, according to a preferred embodiment of the invention, the mixture is at least partially mechanically and/or thermally treated in the hot zone am. and dehydrate.

The advantage obtained by the method of the invention is that the flue gas desulfurization product already has a microcrystalline structure, as it has during the heat treatment and during the reaction involving the hot section 11MK.

Therefore, the anhydride thus obtained can be used as is.
Additives may only be added in special applications.Additionally, the anhydride obtained according to the invention can be mixed with fillers (eg, sand) like known anhydrides.

Furthermore, the anhydride obtained in the present invention can be annealed by a known method.
It can be mixed with I-hemihydrate gypsum to produce multiphase gypsum.

The anhydride of the present invention has a major use in cement setting.
Can be used as a side. In this case, the anhydride of the present invention is
It can be used alone, but it can also be used in combination with gypsum hemihydrate. In this case, the gypsum hemihydrate may be natural or synthetic.

Furthermore, it is advantageous to mix the synthetic anhydride with the dried flue gas gypsum so that it can be used in the cement industry in the final mixture 1.

Compared to the untreated final product "flue gas gypsum", a high value building material is obtained and its market price is high, improving the economics of the flue gas desulfurization process.

1 anhydride from flue gas desulfurization products! ! In a known method for producing calcium sulfite hemihydrate in an aqueous suspension at low values, it is oxidized to calcium sulfite dihydrate by the addition of air. Since the desulfurization product generally contains unreacted collectors, it is possible to obtain a low pH level that is less susceptible to oxidation.
A large amount of sulfuric acid must be added. Oxidation treatment HA
Then, mechanical and thermal dehydration treatment is performed.

Compared to the above methods, the method of the present invention has the advantage that it is not necessary to add sulfuric acid and that the oxidation heat generated when calcium sulfite is converted into calcium sulfate hemihydrate can be used for thermal dehydration. .

The method for producing the synthetic anhydride of the present invention will be further explained with reference to the following examples.

Example 1 Figure 1 shows a system for implementing the method of the present invention.

The exhaust gas from the boiler exits the mailer, is dedusted if necessary, and is then sent to a washing machine to separate sulfur oxides.In this case, the exhaust gas is suspended in the washing machine, including stones. Shake with the solution.This i! suspension for cleaning is used by circulation.

The reaction product &* is taken out as a partial stream t7.4! ! Dehydrate mechanically. For this reason, a wet YACRON and drum filter were used in this example. In order to convert calcium sulfite hemihydrate into two liters of calcium sulfate, air can be blown into the pool after washing. Performing the oxidation in the washer shell is advantageous for mechanical dewatering in the next step. On the other hand, the thermal power of saponification that can be released after heat treatment KIII is reduced, so that if the degree of saponification in the washing tower becomes high, the optimization of the saponification process is lost.

The mechanically dehydrated raw rJL product is sent to a heat treatment unit for further dehydration and to oxidize any calcium sulfite still present. In this case, the heat requirement is obtained wholly or partially from the yc g specific heat. -The required surface energy is the overall K
Or 111! , b″□□! can be obtained by supplying high m# gas or from the combustion air of the power plant and by combustion of (also Fi) fuel.

In the embodiment shown in Figure #1, a suspension having a solids content of about 7-10% by weight is circulated through the washer. $11! Mechanical dehydration is carried out until the residual moisture reaches IQ-15 weight. By blowing air into the washer, more than 95 of the calci sulfite v) A hemihydrate is oxidized to calcium sulfate dihydrate. Finally, the synthetic anhydride is prepared by a two-step heat treatment at a maximum temperature of 5150C. No calcium sulfite remains.

Some properties of the anhydride thus obtained are shown below.

The results of the tests specified in DIN 42011K are shown below.

Recommended uses: Anhydride binder specified by DIN 4208K, cement additive Test results specified by DIN 420B are shown below.

Recommended use: Due to its rapid setting, it can be used as anti-crawling propellant. Example 2 FIG. 2 shows another advantageous apparatus for carrying out the method of the invention. The treatment of exhaust gas is the same as in Example 1.

The partial stream taken off from the washing suspension circuit is partially mechanically pre-dehydrated J1LII. For this reason, K, for example,
Wet cyclones or vacuum filters can be used. The oxidation in the scrubbing tower is carried out solely by the oxygen present in the exhaust gas. The mechanically pre-dehydrated suspension/sludge is heated and dried in a drying device. In this case, waste heat (e.g., exhaust gas before being sent to a decommissioning unit) should be used as much as possible without any expense. The pre-desiccant mixture is then sent to another heat treatment device to remove residual water and oxidize calcium sulfite to calcium sulfate. In this case, most of the heat required for @2 heat treatment step is
It is obtained from the heat of oxidation. If pre-drying can be done with cheap or free waste heat, this I!
In the example, the method of energetically implementing ipHl is υ
is also advantageous.

Embodiment 3 FIG. 3 shows another rounding device system embodying the present invention. ?
Ira's exhaust gas is a must! Depending on the requirements, the product may be passed through a pre-dedusting device to be dedusted to meet the requirements for the final product.

The exhaust gas is then sent to a spray S absorption device which sprays absorbent in the form of a suspension into the exhaust gas. In this case, the suspension is dried by the heat of the exhaust gas. In parallel with the above spraying, separation of sulfur oxides takes place.

The reaction products are separated from the essential waste dust and unreacted dust in a dust separator installed next to the spray absorption device. A portion of the mixture can be returned to the spray absorber to modify absorbent utilization. The remainder is sent to the heat treatment device according to the present invention for treatment. The intermediate product coming from the flue gas desulfurization device is heated in a rotary chamber for about 1 hour at, for example, 45'C in the ninth step of the heat treatment. The material is dried and pulverized in step 11 above. Composition of tube before and after heat treatment Table below: Heat section l! Intermediate product of #J and anhydride after heat treatment (S content analysis value) The above anhydride sample was used in a cement production experiment.

In this case, cement talin, /7
2.713 f and 287 t of anhydride in plain (Bl
ains') was ground 17 so that the specific surface area was 4.0OOos''/f.

In this case, the anhydride cap added to the cement clinker is D
SO as specified in Section 2.2.4 of INl 164 Sheet 1
1 addition @ 3.5% by weight.

The properties of the I Rutland cement thus obtained are shown in the table below.

[Brief explanation of drawings]

1 to 3 show the apparatus system used in the method of the invention. Procedural amendment (method) December 16, 1980 Mr. Commissioner of the Japan Patent Office 1, Indication of the case 1982 Patent application No. 20219'i' 2, Title of invention Process for producing microcrystalline synthetic anhydride 3, Amendment Relationship with the patent applicant's address
Name: Chill Lan Shimbun Tsue Steinmüller Gesell/Yaft Beschlenkter Note Futsung 4, Agent Address: 105 Address: Bussan Building Annex, 1-15 Nishi-Shinbashi, Minato-ku, Tokyo Telephone: 591) 02616, Contents of amendment No changes to the engraving contents of the attached drawing.

Claims (1)

[Scope of Claims] 1. A method for producing a synthetic anhydride in the form of microcrystals from a microcrystalline mixture of flue gas desulfurization intermediate products containing calcium sulfite hemihydrate and calcium sulfate 2 water bodies. ! in the intermediate product by carrying out a heat treatment at a temperature of 200-900°C in the presence of ! m# is dehydrated with calcium hemihydrate-containing component to produce (1) calcium sulfite, and then oxidized (1-) to produce 'trAttllk calcium, while in the intermediate product σ] containing calcium dihydrate # of microcrystalline synthetic anhydride, which is characterized by dehydrating the ingredients! Construction method. 2. If a wet flue gas desulphurization mixture is used, the mixture is at least partially dehydrated mechanically and/or thermally before the heat treatment. 8. Thermal energy necessary for the heat treatment is supplied by external heat supply and by oxidation heat generated in the conversion reaction of (ltaFi)calcium sulfite to calcium sulfate. Or the method described in Section 2.