JPH059073B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an improvement in a method for compressing and dewatering wet sugar beet pulp using gypsum as an auxiliary material. When producing sugar using sugar beet as a raw material, wet sugar beet pulp from which sucrose has been extracted is discharged from a sugar beet extractor. Wet sugar beet pulp usually has a water content of 90 to 91% by weight, and although it is used in some cases in this state, the majority of it is used for feed as a dry pulp after being subjected to compression dehydration and drying processes. The above-mentioned wet sugar beet pulp is produced approximately 45 to 55 tons per 100 tons of raw sugar beet, and is compressed and dehydrated to 77 to 78% water by weight, and then dried to form dry pulp.The thermal energy required for this drying is It accounts for a large portion of the total factory cost. For this reason, measures to reduce the moisture content of compressed and dehydrated sugar beet pulp supplied to the drying equipment include various improvements in the process, such as optimization of sugar beet extraction conditions, improvement of the pressing equipment, and optimization of operating conditions. Alternatively, the use of pressing aids is being considered or implemented. In recent years, attempts have been made to use calcium salts, aluminum salts, etc. as the latter pressing aids, and it has been reported that they are effective in pressing dehydration. The major problem is that some parts of the sugar are transferred to the liquid side during pressing and dehydration, and the liquid side produced by pressing and dehydration usually contains some sucrose and is returned to the sugar beet extraction device, making it undesirable for use. It has also been reported that gypsum (calcium sulfate), which is known as a sulfate of calcium, has low solubility and is effective; however, in actual use, commercially available gypsum (CaSO ₄ , 2H ₂ O) is recommended. If they are simply mixed to form a suspension, there are many problems such as clogging of transport pipes, etc., and a solution that satisfies both effectiveness and ease of handling has not yet been established. In view of the above circumstances, the inventors conducted intensive research to increase the utilization of gypsum as an aid for compressing and dehydrating wet sugar beet pulp. As a result, by mixing cation exchange resin sulfuric acid recycled waste liquid and lime milk, a homogeneous He came up with this invention after learning that a gypsum slurry with good emulsifying properties can be obtained by using a gypsum slurry. Both the cation exchange resin sulfuric acid regeneration waste liquid (hereinafter simply referred to as sulfuric acid waste liquid) and lime milk used in this invention can be easily obtained at sugar factories. It is a regeneration waste liquid generated when a strongly acidic or weakly acidic cation exchange resin is regenerated with sulfuric acid, and an example thereof is shown in Table 1. Table 1 (Unit: g/) Solid content Total sulfuric acid Free sulfuric acid 91 62 27 Lime milk is a milky slaked lime solution obtained by slaked quicklime, and is used as one of the methods for cleaning sugar solution in sugar factories. For use in the current carbonation method, porous and active quicklime obtained by calcining limestone with a CaCO ₃ purity of 98% or higher is usually mixed with water or sweet water (for washing filters treated with sugar solution or Sweetening of various ion exchange resin towers,
Refers to thin water containing some sucrose that is produced during off-gripping. ). The lime milk thus prepared has a CaO concentration of approximately 190 g/m and is extremely homogeneous and milky. In addition, when sweetened water is used for the saccharification, the sucrose in the sweetened water improves the slaked content and further improves the emulsifying property. In order to prepare gypsum from the sulfuric acid waste solution and lime milk, the two may be mixed and reacted under gentle stirring. In this case, it is desirable that the pH of the reaction completed liquid be in the approximately neutral range of 6 to 7. This is because sugar beet pulp is used for feed purposes, so extreme acidity or alkalinity is undesirable. Since the concentration of gypsum prepared from sulfuric acid waste liquid and lime milk is dilute, it is desirable to concentrate it through solid-liquid separation treatment. Various types of concentrators can be used, but for example, if a hydrocyclone is used, solid-liquid separation will occur well.
Gypsum concentration (as CaSO ₄ 2H ₂ O) 200g/
It can be increased to a certain extent. Now, the above concentrated gypsum slurry (gypsum concentration 200
Table 2 shows the case where wet sugar beet pulp was compressed and dehydrated using (g/).

[Table] When gypsum slurry is added, the dehydration rate tends to increase in proportion to the amount added compared to when it is not added, but when 8 to 10 g/Kg dry matter or more is added, the effect gradually decreases. Eventually, an equilibrium state is reached. Gypsum may be added to the wet sugar beet pulp directly as in the above example, or may be supplied to the sugar beet extractor by an appropriate means, but in the latter case, the amount of gypsum added is large. There is a tendency to As described above, the present invention uses a gypsum slurry prepared from sulfuric acid waste liquid and lime milk for compression dehydration of wet sugar beet pulp, thereby suspending conventional commercially available gypsum (CaCO ₄ 2H ₂ O) in water. Problems that occur during use, such as blockage of transportation pipes, poor mixing with sugar beet pulp, or deposition on handling equipment, can be resolved, and manual work can be eliminated.
It is easy to handle, enables automation of operation, and downsizes equipment, resulting in labor and labor savings.It also stabilizes the process, ultimately lowering the energy cost of beet sugar production, and is also useful for waste liquid treatment. It is an extremely practical and useful invention, resulting in cost reduction. Hereinafter, embodiments of the present invention will be specifically explained with reference to Examples. Example Limestone (CaCO ₃ purity 98%) with a diameter of 6 to 10 cm was placed in a cylindrical lime kiln at a ratio of 100 to coke.
12, and the temperature is controlled at 1000-1100℃〓
By burning, a lump of activated quicklime with a purity of 98% of quicklime (CaO) was obtained. This is fed at a rate of 3 to 4 tons per hour to a horizontal rotating drum type slaker (rotation speed: 4 r.pm), and sweetened water with a Bx degree (Brix degree, solid content % measured with a Brix degree meter) of 3 to 4 is supplied. Bx degree is approximately 35
lime milk was prepared. While introducing this lime milk into a reaction tank with a capacity of about 200 ml per hour at a rate of 20 ml per hour, 1.5 ml of Amberlite IR-120B (strongly acidic cation exchange resin) treated with beet sugar solution (Bx degree of about 22) was added to the lime milk. The sulfuric acid waste solution (acidity 0.5N) obtained when regenerated with N sulfuric acid was mixed so that the pH of the reaction solution was in the range of 6 to 6.3 (about 200 times per hour of mixing). The gypsum emulsion obtained by the above reaction was taken out from the bottom of the reaction tank and fed to a hydrocyclone for solid-liquid separation to obtain a emulsified gypsum slurry with a gypsum concentration of 200 g/g. Wet sugar beet pulp (average water content: 90.20% by weight) produced by discharging the gypsum slurry obtained above from the sugar beet extractor
The amount of gypsum was added and mixed using a horizontal U-type mixer so that the amount of gypsum per 1 kg of pulp dry matter was 6.1 g, and then compressed and dehydrated using a Stord MS-64S type press (horizontal twin-screw type), resulting in an average moisture content of 7.24. It was possible to dehydrate down to % by weight. On the other hand, when gypsum is not added to wet sugar beet pulp with the same moisture content, the moisture content after pressing is
It was 77.75% by weight. From this, the addition of gypsum increased the dehydration rate by approximately 3.1% compared to the case without the addition.

Claims (1)

[Scope of Claims] 1. A method for compressing and dewatering wet sugar beet pulp, which comprises using gypsum prepared from cation exchange resin sulfuric acid regeneration waste liquid and lime milk as a press and dewatering aid for wet sugar beet pulp. 2. The compression dewatering method according to claim 1, wherein the gypsum is in the form of a slurry that is concentrated by solid-liquid separation after preparation. 3. The compression dewatering method according to claim 2, wherein the solid-liquid separation is performed using a hydrocyclone. 4. The pressing dehydration method according to claim 1, wherein lime milk is prepared by using sweet water in activated quicklime obtained by calcining limestone. 5. The pressing dewatering method according to claim 1, wherein gypsum is added directly to the wet sugar beet pulp.