JP3144499B2 - PH adjustment method of water using shell quicklime - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the pH of water in rivers, lakes, marshes, aquaculture and fishing grounds using shell lime obtained by firing shells generated in large quantities as industrial waste. is there.

[0002]

2. Description of the Related Art Water from rivers, lakes and marshes, aquaculture and fishing grounds dissolves with various acids such as acids existing in nature, acids caused by man-made factors, or nitration caused by the action of microorganisms of ammonia emitted by fish. Some exhibit weak acidity to strong acidity of about pH 2 to 3. Leaving such acidic water (hereinafter referred to as acidic water) as it is leads to the destruction of the ecosystem and environment of living organisms. Quick lime (calcium oxide), slaked lime (calcium hydroxide) obtained by digesting quick lime, and the like are used as neutralizing agents for neutralizing and reforming acidic water.

[0003] As a technique having a neutralizing action of such acidic water, for example, a technique using calcium carbonate performs neutralization of wastewater or the like using shell fossils produced in specific areas and having components suitable for improving water quality. Squeezing method (JP-A-2-26)
No. 8882, Japanese Unexamined Patent Publication No. 2-268884), a method of neutralizing a shell-like hollow body as a contact filter medium for retaining microorganisms in a contact aeration type sewage treatment apparatus (Japanese Patent Publication No. Hei 2-2635). Gazettes) are known. The technique using calcium oxide is a technique for deoxidizing mainly acidic waste oil and waste liquid using an alkaline agent obtained by mixing calcium oxide powder obtained by firing shellfish, bone, limestone, etc., water and oil ( Japanese Patent Publication No. 2-32208) is known.

As described above, limestone, quicklime or slaked lime is a material which is easily available and economically suitable, and is therefore frequently used as a neutralizing material for acidic water. However, for example, a method using calcium carbonate such as limestone has an advantage that it can be used in a lump, but has a small pH adjusting ability as compared with quick lime or slaked lime, and therefore requires a large amount for neutralization of acidic water. On the other hand, quicklime and slaked lime have a large pH adjusting ability, so that they can be used in a smaller amount than limestone, but have a problem that they become powdery and cloudy in water. In addition, in the case of neutralizing and reforming acidic water, a method of neutralizing rapidly by adding a predetermined amount of quicklime or slaked lime which has a large neutralization capacity if the treatment is only neutralization and has a high neutralization speed. Although it can be adopted, when it is necessary to neutralize while maintaining the biological ecosystem such as a river or a lake, the above method is not a preferable method. On the other hand, when calcium carbonate such as limestone is used, neutralization is generally milder than quick lime or slaked lime, but on the contrary, it takes too long to neutralize, microorganisms adhere to the limestone surface, and sludge accumulates. The surface is covered, and the neutralization ability is reduced. In addition, a method of neutralizing and reforming acidic water using quicklime whose digestion rate has been adjusted is also conceivable.However, as a method of adjusting the quicklime digestion rate, calcium carbonate produced by aquatic ecosystem origin is used as a raw material, and after calcining In the presence of nonionic, anionic and cationic surfactants, grinding of quicklime and coating of quicklime surface with surfactant in a single operation, and adjusting the thickness of the coating layer to digest quicklime A method for adjusting the speed is known (JP-A-2-258656). However, in the method of neutralizing and modifying acidic water using quicklime coated with quicklime and adjusting the digestion rate by coating a surfactant in this way, a step of coating the quicklime with a surfactant is required. In addition, since quicklime is pulverized in the presence of a surfactant, quicklime powder is likely to flow out and become cloudy, and a device for preventing it is required.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problem of using conventional quick lime in a method of using calcium oxide as a neutralizing agent in the neutralization and reforming of acidic water, and solves the problem of the ecosystem of living organisms. Of water that can be neutralized while maintaining
An object of the present invention is to provide an H adjustment (neutralization reforming) method.

[0006]

Means for Solving the Problems As a result of intensive studies on the method of adjusting the pH of water, the present inventor has found that the above object can be achieved by using quicklime produced by a specific method, and has completed the present invention. did. That is, the present invention is a method for adjusting the pH of water, wherein the pH of the water is adjusted using quick-lime shell lime produced from shells and having a low digestion rate. Rotary kilns, vertical quicklime calcination furnaces, and the like have been used as apparatuses for baking shells. Since these devices are generally of the type in which the calcined product is rapidly cooled, the quick lime obtained from the shell often has a high digestion rate. In the method of the present invention, the shell was produced as a raw material,
It is characterized by using quick lime of a shell having a total digestion reaction time of 60 minutes or more as measured by a measurement method described later. Shell quicklime that can be used in the present invention can be obtained by the following method. In the conventional vertical lime sintering furnace (FIG. 3), the insertion portion 2 of the raw material charging pipe 1 in the furnace is eliminated, and the invasion of the outside air into the rotary seal portion and the shunt portion 6 of the mining machine 5 can be prevented. The cooling rate of the calcined material is adjusted by using a vertical lime calciner having an improved structure in which a cooling pipe 10 capable of adjusting the amount of air is provided in the ore removing unit 5 while adjusting the amount of cooling air. By adjusting the value, quick shell lime that can be used in the present invention can be obtained. FIG. 4 shows a schematic overall sectional view of an improved vertical lime burning furnace (hereinafter simply referred to as a furnace).

[0007] The outline of the production process in the case of producing shell lime using the above furnace is as follows. First, the particle size of the shell charged into the furnace is preferably about 2 to 60 mm.
Large oyster shells, abalone shells and the like are previously crushed to a particle size within the above range, preferably about 30 to 50 mm, using a suitable crusher to adjust the particle size. By adjusting the shell particle size in this way, charging into the furnace is facilitated, the shell interior filling bulk density is increased, and the air resistance of the furnace deposition area is increased to control combustion air. Becomes easier. If the size of shell pieces exceeds 60 mm, the bulk density inside the furnace will be low, and the air resistance will be low, making it difficult to manage the baking. If it is less than 2 mm, it will be liable to fly and will flow out of the furnace together with the exhaust gas. Is not preferred.

[0008] Shells (hereinafter simply referred to as shells) whose grain size has been adjusted are charged from a raw material charging pipe 1 and temporarily deposited on a shelf 3 in the furnace. Therefore, shells can be inserted into the ceiling of the shelf 3 so that combustion air in the furnace does not easily escape to the exhaust gas passage 7 outside the shelf. For this reason, the air resistance of the shelf 3 increases, and the combustion air does not easily escape, and a stable firing atmosphere can be maintained.

Next, the shells temporarily deposited on the shelf 3 are sequentially dropped into the firing zone 4 and fired. The calcination of the shell can be usually carried out while maintaining the temperature of the calcination zone 4 at about 1,100 ° C. to 1,250 ° C., and the temperature and the holding time are the desired degree of calcination of the shell quick lime, ie, the shell lime. What is necessary is just to set suitably according to calcium oxide content. Here, firing is controlled mainly by controlling the amount of fuel and combustion air used, but if there is outside air entering the furnace, it becomes difficult to control firing, and quality fluctuations such as so-called unevenness in burning are likely to occur, resulting in the calcination of shell lime. Quality control becomes difficult. The main path of the outside air in the conventional vertical lime calcination furnace is the rotating section of the shut section 6 and the mining machine section 5. In particular, the shut portion 6 serves as a main cooling air intake for the calcined shell quicklime, but since it is open to the outside air, it is difficult to control the amount of air to be taken in. The structure was such that air was taken into the furnace.
First, as means for preventing the invasion of outside air, the conventional mining machine 5
The rotary seal portion (FIG. 5) of FIG. 5 has a double seal structure (FIG. 6) to prevent intrusion of outside air from the rotary seal portion of the mining machine portion 5,
In addition, the shoe which is the main intake of the conventional cooling air
For example, a damper 9 which is driven by an air cylinder is attached to the start portion 6 in a double structure, and the dampers are alternately operated to discharge the shell lime and prevent outside air from entering the shoot portion 6. And the like. As means for taking in cooling air, as shown in FIGS. 7 and 8, a cooling pipe 10 for taking in cooling air is provided in the mining machine section 5, and inside the mining machine section 5. Adjusting the cooling air according to the desired shellfish digestion rate and sending it in,
Examples of such methods include cooling shell lime.

The digestion rate (hydration rate) of the shell lime can be adjusted by adjusting the cooling rate of the shell lime thus calcined. The cooling rate may be adjusted according to the desired quick lime digestion rate. To slow down the rate of shellfish lime digestion, slow down the cooling rate (slow cooling),
Further, if the firing temperature is set higher, there is a further effect. The reason why the slow cooling slows down the quicklime digestion rate is thought to be that the slow cooling causes the crystals to become coarse and the digestion rate to slow down.

In order to neutralize and reform the acidic water, for example, the powdered portion of the calcined lime obtained by calcination using the above-mentioned furnace is removed and put into a container, and the lime is brought into contact with the acidic water. Just do it. There is no particular limitation on the container in which the shellfish lime is to be placed, as long as it has a structure that allows the shellfish lime to easily come into contact with acidic water and is not easily corroded by alkali or water. Any shape may be used according to the conditions. Examples of such a container include a net having a small mesh and a cloth bag as shown in FIG. Further, the container containing the shell lime may be fixed in an acidic water by an appropriate method, and the fixing method, the number of containers to be fixed, and the like are not particularly limited.

[0012] As described above, by using shell lime having a slow digestion rate for neutralizing and reforming acidic water, quick lime obtained by calcining conventional limestone is immediately powdered while generating heat due to contact with water. For the phenomenon of cloudiness,
Since digestion proceeds gently, there is little heat generation, very little clouding due to slaked lime generated by digestion, and it is possible to neutralize and reform acidic water while maintaining ecosystems of living organisms such as rivers and lakes.

EXAMPLES Hereinafter, the method for neutralizing and modifying water using quick lime of the present invention will be described in detail with reference to examples.

(Example 1) Scallop shells crushed to a particle size of 50 mm or less were used as raw materials for the production of quick lime.
This raw material was put into a vertical lime calcination furnace from a raw material charging pipe 1 and baked at a temperature of 1,100 ° C. in a calcination zone 4 for 1 hour.
After calcining, the shell quicklime was cooled while gradually cooling to about 100 ° C. or less over about 8 hours by adjusting the amount of cooling air, the shell quicklime discharging speed, and the like. The calcined degree (CaO content) of the obtained quick lime was 90%. For the production of shellfish lime, a vertical lime calcination furnace obtained by improving a conventional vertical lime calcination furnace to the following example was used. That is, while eliminating the insertion portion 2 of the raw material shell input pipe 1 in the furnace, the rotary seal portion of the mining machine unit 5 has a double seal structure, and the shut unit 6 is operated by an air cylinder. A double damper 9 is installed, and the dampers are alternately operated to take out the shell lime so as to prevent the outside air from entering the furnace, and to control the cooling rate of the fired shell shell lime. 10 was improved to a vertical lime sintering furnace attached to the mining unit 5.

Next, in order to investigate the digestion state of the shell lime, the shell lime cooled to room temperature was sized 30 m.
Approximately 500 g of a net having a particle size of about m was put into a mesh net, and the net was left immersed in 100 l of water for 20 days. Thereafter, the net was taken out of the water, and the digestion state of the individual shell lime was examined. As a result, it was found that about 1/3 of the state of the shell lime before immersion in water was powdered. Further, as a result of analyzing about 2/3 of the components remaining in shape, about 75% of slaked lime was found, and the remaining components were calcium carbonate.

(Example 2, Comparative Examples 1 and 2) Quicklime was prepared under the conditions shown in Table 1 and the digestion rate of quicklime was investigated.
Table 1 shows the obtained results. From this result, it can be understood that the quicklime of the shell obtained by slow cooling has a slow digestion rate and also generates less heat due to the digestion. In addition, the quicklime of the shell of Example 2 was obtained by using the scallop shell according to the operation of Example 1.
It is obtained by firing in an improved vertical lime firing furnace,
The quicklime of Comparative Examples 1 and 2 was prepared by sintering the scallop shell and limestone in an electric furnace at 1,000 ° C. for 2 hours, then taking out into the atmosphere and rapidly cooling. The quick lime digestion rate was measured according to ASTM C110-76a defined by the American Society for Standards for Materials. The outline of this method is as follows. Using a digestion reactivity test apparatus, 3.3 ml of 380 ml of water at a water temperature of 40 ° C.
5 mm sieve passing sample quicklime was quickly prepared, and 76 g of quicklime placed in an airtight container until room temperature was reached,
The temperature was read until the reading of the thermometer was changed continuously within 0.5 ° C. three times, and the first time of the three readings was taken as the total digestion reaction time, and the temperature at this time was regarded as the final reaction temperature. In this method, the initial temperature is subtracted from the final reaction temperature to obtain a total temperature increase.

(Example 3) Shell lime obtained in Example 1 was sorted to a particle size of 10 to 50 mm, slaked lime having a size of 30 mm and limestone having a size of 2 to 5 mm were used as neutralizing agents. The pH value for each neutralizer is 2.
50 g of a neutralizing agent was added to 10 l of water adjusted to about 5, and 1
After stirring appropriately at a frequency of twice a day, the mixture is allowed to stand, and p
H was measured. FIG. 2 shows the results of measuring the change in the pH value (vertical axis) with the passage of time (horizontal axis). In FIG. 2, changes in pH values of the slaked lime, shell quicklime and limestone are indicated by 11, 12 and 13, respectively. from this result,
It can be seen that even shellfish lime having a low hydration rate has a neutralizing ability substantially equal to slaked lime.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a case in which quicklime is added to a shell.

FIG. 2 is a graph showing the neutralizing ability of each neutralizing agent.

FIG. 3 is a schematic cross-sectional view of an entire conventional vertical lime calcination furnace.

FIG. 4 is a schematic cross-sectional view of the entire improved vertical lime burning furnace.

FIG. 5 is a conventional rotary seal unit of a mining machine unit.

FIG. 6 is an improved schematic diagram of a rotary seal part of a mining machine part.

FIG. 7 is a schematic diagram of a pipe for improving a shout portion and cooling.

FIG. 8 is a schematic diagram of a cooling pipe as viewed from a shout portion side.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 raw material introduction pipe 2 raw material introduction tube furnace insertion section 3 shelf 4 firing zone 5 mining machine section 6 shout section 7 exhaust gas passage 8 ceiling brick wear section 9 damper 10 cooling pipe 11 pH change due to slaked lime Situation 12 Change in pH value due to shell lime 13 Change in pH value due to limestone

[Table 1]

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 1/66 C04B 2/00

Claims (3)

(57) [Claims] Claims 1. A shell lime manufactured from a shell as a raw material.
A method of adjusting the pH of water using the method of adjusting the pH of water,
Using a digestion reactivity test device, 380 m of water at a water temperature of 40 ° C.
Quickly prepare 3.35mm sieve passing sample quicklime in l
And quicklime 7 which was put in the airtight container until it reached room temperature
6 g, and the reading of the thermometer is within 0.5 ° C for 3 consecutive times.
Read the temperature until it changes, the first of these three readings
Time is defined as the total digestion reaction time.
Measurement method according to ASTM C110-76a specified by
60 minutes total digestion reaction time of the shell quicklime measured in
A method for adjusting the pH of water characterized by the above . 2. The shell lime is made of 110% shellfish.
Shell quicklime manufactured by firing at a temperature of 0 to 1250 ° C
The method for adjusting the pH of water according to claim 1. 3. The particle size of the shell lime is 10 to 50 mm.
The method for adjusting the pH of water according to claim 1.