SU367204A1 - LIBRARY | M. Cl. D 21c 3 / 10UDK 661.728.2 (088.8) Authors of the invention I. P. Kara, A. G. Terekhov, A. S. Zhuk, V. V. Gromov, Yu. A. Kolobkov, V. V. Shishin, G. B. Tsaplov, N. G. Novozhilov, V. F. Korenevsky, A. K. Keze, K. A. Veinov, M. D. Babushkina, E. V. Babaevi G. G. Bratchikov - Google Patents

Description

The invention relates to the pulp and paper industry, in particular to a method for preparing cooking liquors for producing sulphite pulp.

Recently, sulphite pulp cooking with the use of cooking solutions on a magnesium base has become particularly popular.

A known method for producing sulfite cooking acid on a magnesium base is that natural magnesium-containing raw materials, such as magnesite, are calcined and milled, and powdered magnesium oxide is hydrated at about 100 ° C and the resulting magnesium hydroxide suspension is fed to absorb sulfur dioxide. anhydride.

In order to expand the raw material base and improve the Process, a method has been proposed for producing sulphite cooking acid on a magnesium base, consisting in the use of the natural mineral, brucite, as the magnesium-containing raw material.

The proposed method is simple, cheap and makes it possible to obtain high-quality cooking acid. Brucite contains up to 98% crystalline magnesium hydroxide. The use of brucite as a magnesium-containing raw material in the preparation of sulfite cooking acid on a magnesium base allows

eliminate the operations of obtaining magnesium oxide and its hydration, which greatly simplifies the process.

The method involves the absorption of SO with an aqueous suspension of ground brucite (domestic natural crystalline magnesium oxide hydrate) in order to obtain a crude bisulfite solution on a magnesium base.

When using brucite, roasting and hydration operations are excluded, and for the rest the technological process of preparing magnesia raw materials (in this case brucite) and obtaining sulfite sulphite solution

on a magnesium base, but the nature of the onerities is not complicated.

For the preparation of sulfite cooking acid on a magnesium basis,

The well-known, but partially modernized absorption equipment was installed, namely instead of combination bubble columns equipped with fail-type strainer plates, with an additional reactor

it is foreseen to use pillars of a subfloor construction, but with recycling

these are part of the working fluid, which eliminates

the need for additional reactor reactor.

The technological scheme of the proposed method for obtaining a sulfite bisulfate solution on a magnesium base is shown in FIG. one.

The process uses the following equipment: bubble absorbers (columns 1 n 2) with 15-20 perforated trays; tank 3 for preparing brucite slurry; flow tank 4 working suspension brucite; a continuous sump 5 for separating the coarse portion of the imam from the solution; filter 6 with gravel or other zapolpepiy1M for a boggy bleach solution; pumps 7; automatic pH meters 8.

Sickle gas, produced by any of the known methods and content of 10-15% of F3, enters the lower part of the column and, after passing through the openings of all its plates, is fed to the lower part of column 2, after which it is emitted into the atmosphere. The concentration of SO- in the exhaust gas is thus zero due to the automatic regulation of the process of trapping sulfur dioxide.

Brucite working suspension, having a particle size of 50–60 microns, containing weight. % MgO and prepared: periodically or continuously in a tank 3 equipped with an agitator, is sent to the supply tank 4, where, at a temperature of 40-50 ° C, it is put into the irrigation tank of each column at a temperature of 40-50 ° C immediately before the circulation flow. The amount of brucite suspension supplied continuously to each of the smokes is regulated by special shut-off devices in accordance with the readings of continuously operating pH meters, which measure the pH value of the liquid supplied to the column.

At the same time, a liquid passes into column 2, containing a certain amount of Mg (OH) 2 and MgSOs in solid form. The pH of such a liquid is maintained within the range of 5-6 in order to maximize the degree of extraction of SO from gas. The higher pH of the liquid supplied to the colopp /, is lower due to the higher proportion of free SO2 in the solution and, depending on the concentration of the prepared solution in terms of SOa, is in the range 3.5-4.5. At the outlet of the column / solution, depending on the requirements of the cooking process, it contains 3.5-6% of total SOa at a concentration of 50-55% of the total amount of sulfur dioxide.

The solution obtained in column 2 contains 2–4% of total SO2 with a proportion of pure SO of about 55–60%. The temperature of the liquid, depending on the temperature of the initial suspension of brucite and the composition of the resulting solution, is maintained in the range of 40-70 ° C.

Each column (see Fig. 1) is also irrigated with a circulating solution, which is necessary both to increase the contact time of SOa and Mg (OH) 2 and to maintain the pH value within the specified limits.

Derived from coloipa / solution has, as a rule, a certain amount of miperalpogo residue (up to 3-4 wt.%). For separation

for the coarser fraction of this residue, the solution is passed through a settling tank, and for more To; through cleaning, through the filter 6 with gravel or another filtering material. When working on raw materials containing a small number of impurities, one of these cleaning units can be excluded from the technological scheme.

The second is the technological scheme,

the purpose of which is to obtain an acidic bisulfite solution of magnesium (the content of free SO2 is more than 50% of the total), is presented in fig. 2. This option has the following features.

As in the basic version, a sulfite-bisulphite solution is obtained in column 2, but its tenacity in general S02 is slightly lower at a rate of 2–3%, with a corresponding decrease in the concentration of bound S02 as well.

The solution transferred from the contour of the column 2 to the contour of the column / is cooled in a special heat exchanger 9 from 40-50 ° to an approximate 12-16 ° C, and a part of this solution is attached to the solution in front of the heat exchanger

of the finished unclarified solution, in order to avoid clogging of the working surface of the heat exchanger with magnesium sulfite crystals, since the solubility of the last ori ga 1 rP 5-6 and the specified temperature change

greatly reduced. By adding a portion of the finished solution containing about 60% free SO2, the pH of the cooled liquid is reduced so that crystallization of sulfite from the solution does not occur.

Cooled to 12-16 ° C, the solution is fed to the column /, where it is strengthened with strong sickle gas to 3.5-4% for total S02, and the fresh suspension of brucite here

do not add. Due to this, the content of free S02 in the finished solution rises to 60-63% of the total amount of SOj. As magnesia raw material according to the proposed method, it is provided for the use of the mineral brucite, the deposits of which have recently been discovered in the Far East; Brucites of these deposits - Kuldur and deposits of the South Khingan group - represent natural crystalline magnesium oxide hydrate, which contains as impurities in the form of disseminated minerals SiO2 and CaO, and, moreover, a very small amount of sesquioxides.

Brucite containing not less than 60% MgO (theoretical MgO content in brucite 69%) and up to 6-7% SiO2 and CaO (in total) can be used.

subject matter

The method of obtaining sulfite cooking

Magnesium-based acids by sorption of sulfuric anhydride with an aqueous suspension of Zium magnesium-containing raw material, characterized in that, in order to expand the raw material base 6 of the process improvement, brucite is used as the magnesium raw material.

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