JPS60232201A - Pressing method in high pressure crystallization - Google Patents

Abstract

PURPOSE:To make it possible to protect the internal structure of a filter without imparting excessive load thereto, by avoiding the application of excessive load to the solid of collected components in a range not lowering the product purity of said components. CONSTITUTION:In a process wherein the solid component, after a liquid component to be removed is almost filtered, is further pressed to take out said component to be removed, pressing piston pressure PP is stepwise or continuously lowered to suppress the difference of the piston pressure PP and liquid pressure P1 (pressure Ps applied to a solid) from becoming excessive. As a result, a specific component can be collected as a solid with suitable purity and collection efficiency without applying excessive load to a high pressure container structure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting a liquid component from a high-pressure container by applying pressure to a solid-liquid coexistence state reached by high-pressure cubic crystallization and squeezing it.

In the high-pressure crystallization method, a raw material such as a mixed liquid or slurry consisting of multiple components is introduced into a high-pressure container equipped with a filter, and high pressure is applied to the raw material such as the mixed liquid or slurry to crystallize specific components. This is a way to promote this.

By this operation, a state is obtained in which the crystals of the specific component (hereinafter sometimes referred to as the captured component) and the liquid of the remaining liquid phase component (hereinafter sometimes referred to as the removed component) are mixed. Therefore, the outlet drain pipe is unblocked, pressure is applied to the solid-liquid coexistence state, the liquid removed component is discharged from the system via the filter, and then the lid of the high-pressure container is opened or the container itself is removed. The assembly is released, and the solid collection component remaining in the container is taken out of the container as it is or after being dissolved and used as a product.

In other words, if the pressure crystallization procedure is divided into process units, it can be roughly divided into the above-mentioned raw material introduction, pressure crystallization, filtration/squeezing, and solid body extraction, but all of them involve considerable high pressure, so they are commonly used. It is not possible to just transfer the temperature crystallization method as is, and various issues must be overcome in each step before the high-pressure crystallization method can be implemented industrially.

The filtration/squeezing process according to the present invention also has the following problems. That is, filtration and compression are performed between the pressure crystallization step and the solid extraction step, and there are special circumstances in which the filtration and compression operations themselves are performed under high pressure. Therefore, unlike the general temperature crystallization method, it is not possible to perform the crystallization operation and the filtration/squeezing operation separately and independently using containers or equipment suitable for each. It must be understood that these containers and devices are operated under conditions that are interrelated with each other but cannot be said to be completely independent. Therefore, even in the filtration/squeezing process, pressure crystallization is still ongoing. For example, if excessive squeezing pressure is suddenly applied, the solids tend to become excessively compacted at the front of the filter, increasing filtration resistance. Therefore, there is a danger that the removed components may remain or some of the removed components may solidify due to the compaction, leading to a decrease in the purity of the collected components. Furthermore, if the final compression pressure is maximized, it may cause damage to the sifter structure that blocks outflow of minute amounts of liquid phase components remaining inside. Therefore, the present inventors set the standard of reducing the liquid pressure after passing through the filter (the discharge pressure of the removed components), and if necessary, further reduced the unseparated mother liquor (liquid removed components remaining in the pressure vessel). ) by controlling the pressure so that it does not accumulate, the surface of the solid collection component that is compacted on the front of the filter is melted, improving the purity of the collection component crystal itself and promoting the discharge of furnace liquid. See the completion of the technology to
Tokukai 8i already! 354-52678, 54-5336
It is disclosed as 2.

The present invention was made as a result of studying the actual situation of the filtration/squeezing process from another perspective.As mentioned above, the pressure crystallization and the filtration/squeezing are performed in the same container or device,
The purpose of this method is to eliminate as much as possible the various difficulties that may arise from the fact that squeezing is carried out under high pressure following the pressure crystallization step, and in particular, By avoiding excessive load on the solids of the captured component within the range where the true value of the product line does not substantially decrease, for example, the internal structure of the filter etc. is not subjected to more than necessary load. The aim is to establish a compression separation method that can protect these substances.

The compression separation method of the present invention that satisfies the above objectives is based on the fact that the liquid removed component is 1? If the solid component after filtration is further compressed to remove the removed component from the filter,
The gist of this method is to suppress the load of excessive pressure on the solid collection component by lowering the squeezing piston pressure stepwise or continuously.

FIG. 1 is a pressure change diagram when the present invention is not carried out, where P is the pressure corresponding to the piston load (referred to as piston pressure in this specification), and is abbreviated from the beginning to the end of the filtration/squeezing process. A certain amount of pressure is applied. On the other hand, P1 is the liquid pressure behind the filter (on the atmospheric pressure side) and indicates the pressure inside the drain pipe before being taken out to atmospheric pressure. In other words, when entering the filtration/squeezing process, the closure of the outlet drain pipe is released, and the piston is lowered to apply piston pressure to the treated material in a solid-liquid coexistence state. Appears on the back side of the filter with the same pressure as Pp (liquid pressure Pl), and is discharged into the atmosphere through the drainage pipe, but eventually the liquid removed component in the material to be treated is filtered out, and the inside of the high-pressure chamber is apparently solid. It will be filled with the collected components. However, when observed microscopically, a considerable amount of mother liquor remains between each crystal of the scavenging component, and at this stage, the stone that completes filtration and the liquid removed component are included between each crystal of the scavenging component. As a result, the purity of specific components in the collected solids becomes dramatically lower. Therefore, in this state, the filtration is not stopped and the piston continues to be lowered to squeeze out the solid captured components, but at this time the amount of gold p liquid passing through the filter is smaller than in the previous stage of filtration. Therefore, the hydraulic pressure P1 gradually decreases as shown in FIG. 1, and the differential pressure Ps with respect to the piston pressure P gradually increases. However, the piston pressure P is constant, and the hydraulic pressure Pl
Since this decreases, the differential pressure P8 can be considered to be the pressure acting on the solids remaining before the filter, and the pressure P applied to the solids gradually increases. Therefore, under pressure action conditions as shown in Fig. 1, in the final stage of squeezing, all of the piston pressure acts on the solid and the filter (filter is generally used for squeezing by the piston) The filter is arranged in a direction perpendicular to the filter, so that the liquid can easily pass between the layers of the compressed solid and be discharged), and friction occurs between the filter and the filter. However, there is a problem in that the filter, its support, and other various structures are overloaded and have an adverse effect on them. In particular, it significantly shortens the life of the filter, leading to increased maintenance costs, and there is also the problem that the production line must be stopped while parts are replaced, reducing productivity. In addition, there is also an element in which the solids that come into contact with the filter melt due to the frictional heat caused by the friction (an element in which minute solids flow out from the filter gap), and these are immediately filtered to the rear of the filter, reducing the collection rate of specific components. The problem of a disadvantage in that the pressure decreases also arises when excessive squeezing pressure Ps is applied.

Therefore, in the present invention, the piston pressure P is reduced by decreasing the piston pressure P in stages as shown in FIG. , and the difference between the liquid pressure P1 (pressure Ps applied to the solid
) is suppressed from becoming excessive, thereby preventing the occurrence of the above-mentioned adverse effects. The timing at which the piston pressure begins to decrease and the extent to which it is decreased vary depending on the structure of the high-pressure crystallizer, the type of equipment material, the degree of crystallization operating pressure and squeezing pressure, and the properties of the raw materials and crystals being handled. As for the point at which the piston pressure starts to decrease, one example is a method in which the above-mentioned outflow point of the solid component is detected and the pressure is decreased from the point at which the symptom appears. The melt of the specific component melted by the frictional heat immediately passes through the filter and acts in the direction of increasing the fluid pressure P1 (see Figure 4), so if you capture this point and lower the piston pressure, At least a little overload on the filter can be suppressed to a minimum. Although the subsequent reduction in piston pressure can also be controlled freely, for example, as shown in FIG. 5, a method may be adopted in which the pressure is reduced in stages every time a temporary increase in the hydraulic pressure PH is observed. However, from an industrial perspective, P when specific raw materials and specific equipment are used.

The behavior of Pl is almost the same and can be operated based on preset conditions.

Next, as for the method of lowering the piston pressure, any means can be adopted depending on the design of the pressurizing device (for example, a hydraulic circuit), but Fig. 6 shows an example of a stepwise lowering method. FIG. 7 shows an example of the continuous reduction method. In these figures, 1 is a relief valve designed with a large set value, 2 is a relief valve designed with a small set value, 3 is a solenoid valve, 4 is a check valve, and 5 is a variable set value type relief valve. Although the present invention uses a piston-cylinder type high-pressure device for convenience, there is no reason to limit the structure of the device to this, and the device can be adopted to any structure including a high-pressure device having an external pressurizing mechanism.

Since the present invention is configured as described above, it is possible to collect a specific component as a solid with appropriate purity and collection rate without overloading the high-pressure vessel structure.

[Brief explanation of drawings]

FIG. 1 is a pressure control diagram in a conventional example, FIGS. 2 to 5 are pressure control diagrams in an example of the present invention, and FIGS. 6 and 7 are hydraulic circuit diagrams suitable for changing piston pressure. Applicant Kobe Steel Co., Ltd. Maruzen Engineering Co., Ltd. Kinsha Shin 6th Section, Figure 4 Time □ Time □ 2F v IIJ Figure 7

Claims (1)

[Claims] Pressure is applied to the solid-liquid coexistence state under high pressure reached by high-pressure crystallization, and when the liquid component is taken out of the high-pressure container, the solid component is further compressed after the liquid component has almost been treated in the furnace. In the process of extracting the liquid component from the filter,
A squeezing method in high-pressure crystallization, characterized in that the load of excessive pressure on solid components is suppressed by lowering the pressure stepwise or continuously.