KR100339884B1 - modifier for precipitate and method for preparing it - Google Patents

Abstract

The present invention relates to a medicament for preventing water pollution by improving sediment in seawater, rivers, and fish farms. The object of the present invention is to purify the water quality of fish farms without death of aquatic products and benthic organisms, and to prevent red tide. The present invention provides a sediment improver and a method for preparing the same.

The present invention for achieving the above object,

Activated calcium hydroxide with an activity of 200 or less: 5% by weight or less, water-soluble iron: 0.1-1% by weight, and a precipitate improving material composed of active magnesium hydroxide and other unavoidable impurities having a remaining activity of 100 or less; Dehydrating the magnesium hydroxide slurry generated in the seawater magnesium production process;

Vacuum molding the dehydrated raw material into particles;

Drying the molded particles; It relates to the technical subject of the method for producing a precipitate improver comprising a.

Description

Sediment modifier and its preparation method {modifier for precipitate and method for preparing it}

The present invention relates to a medicament for preventing water pollution by improving sediment in seawater, rivers, and fish farms, and more particularly, to a sediment improver capable of removing water pollution sources of fish farms without the death of aquatic organisms and microorganisms. will be.

In recent years, land sewage such as living sewage, manure, factory discharge water, fertilizers and pesticides are indiscriminately introduced into the sea or rivers, and various food wastes and aquaculture products excreted from aquaculture farms, along with land pollution, As they accumulate at the bottom, they are decayed by bacteria, deteriorating the environment inside the fish farm.

When these accumulators decay, hydrogen sulfide and nutrients of microorganisms, nitrogen and phosphorus, which are toxic to aquatic organisms, are supplied to produce green algae or red algae to reduce dissolved oxygen in water. In addition, by generating toxic plankton, aquaculture products such as fish and shellfish and algae in aquaculture farms are killed, and aquatic product productivity is reduced. Furthermore, it causes a lot of damages by destroying human life and environment. Of course, strict restrictions on the inflow of wastewater, including nutrients, and removal of food waste and excreta from aquaculture can reduce the damage, but this is practically difficult.

In order to reduce such damage, the bottoms are removed or sprayed with quality improvers. As the quality improvement agent, lime, loess, clay type, magnesium hydroxide are mainly used.

Spraying lime (CaO) turns gypsum (CaSO ₄ , 2H ₂ O) into sulfate ions (SO ₄ ⁻ ) in water. Gypsum, a product, forms a dense film on the bottom of the sea to block dissolved oxygen in the water, causing the shellfish and aquatic organisms to inhabit the lower part of the gypsum film, causing fisheries to be devastated. In addition, the degradation of fisheries is aggravated by blocking the reaction of the sprayed agent to remove hydrogen sulfide, ammonia and phosphorus generated from the accumulation material. Ocher adsorbs emulsifiers and settles to the bottom, but these deposits form a film and cause problems such as lime spraying. High soils dissociate into magnesium and quicklime when sprayed, which causes low solubility in water, causing problems like lime.

The present invention provides a sediment improving agent and a method for producing the same that can purify the water quality of aquaculture fisheries and prevent red tide without the death of aquatic products and benthic organisms.

1 is an example of an experimental apparatus applied to find out the change in chemical composition and appearance of the sediment improver in seawater

Sediment improver of the present invention for achieving the above object is composed of active calcium hydroxide of less than 200 activity: less than 5% by weight, water-soluble iron: 0.1-1% by weight, active magnesium hydroxide of the remaining activity of less than 100 and other unavoidable impurities .

In addition, the method for producing a precipitate improving agent of the present invention,

Dehydrating the magnesium hydroxide slurry generated in the seawater magnesium production process;

Vacuum molding the dehydrated raw material to obtain particles;

It is configured to include; drying the shaped particles.

Hereinafter, the present invention will be described in detail.

In the present invention, the active agent is used to improve the removal efficiency by fast reaction with contaminants by controlling the compounding ratio of the improver component so as not to form a film on the surface of the sea water or the river bottom.

The precipitate improver of the present invention includes magnesium hydroxide, calcium hydroxide, and water-soluble iron, and magnesium hydroxide and calcium hydroxide are those having high activation.

Magnesium hydroxide is effective in removing harmful substances such as hydrogen sulfide and ammonia, which are toxic to aquatic organisms, but its solubility in water is about 0.009%. Therefore, in the present invention, in order to increase the reaction rate of magnesium hydroxide, one having an activation degree of 100 or less is used. If the activation degree exceeds 100, the removal amount of T-S (Total-Sulphur) in the precipitate is not large.

Calcium hydroxide reacts with harmful substances to improve the precipitate, but when the amount is too high, it reacts with sulfate ions in water to produce calcium sulfate (CaSO ₄ · 2H ₂ O; gypsum). Since it will become high, it is preferable to set it as 5 weight% or less. Calcium hydroxide is also preferably used less than 200 to increase the efficiency of removing contaminants.

In the present invention, water-soluble iron should be at least 0.1% by weight as an essential nutrient of all aquatic organisms, and can be expected to be effective for fish, shellfish, etc., and if it exceeds 1% by weight, it reacts with sulfides in water to produce toxic substances, which is toxic to aquatic organisms. To hinder sediment improvement.

The precipitate improving agent of this invention can mix | blend the raw material of magnesium hydroxide, calcium hydroxide, and water-soluble iron powder. At this time, magnesium hydroxide and calcium hydroxide may be activated and blended, respectively, or may be blended and then activated. Examples of active magnesium hydroxide include those activated by using natural magnesia sites, brucite and dolomite as plastic raw materials. Examples of activated calcium oxide include quicklime made by calcining limestone, calcareous lime, and calcined shellfish and oyster shells.

In the present invention, the magnesium hydroxide slurry generated in the seawater magnesia production process is treated by dehydration, vacuum forming, and drying to obtain the precipitate improver composition of the present invention.

Normally, seawater magnesia is obtained by reacting purified seawater with produced ash (CaO) to form a magnesium hydroxide slurry, and drying and firing the magnesium hydroxide slurry. Representative examples of the composition of the magnesium hydroxide slurry are shown in Table 1 below.

Chemical composition (% by weight) MgO CaO SiO ₂ F3 ₂ O ₃ + Al ₂ O ₃ Ig-Loss 92-98 0.6-2.0 0.2-3.0 1.0-3.0 1.0 or less

As can be seen from Table 1, the magnesium hydroxide slurry generated in the seawater magnesia manufacturing process has a high content of MgO, CaO content of less than 5% while containing water-soluble iron, it can be seen that it can be usefully used as an improving agent of the present invention Can be.

In the present invention, to activate the magnesium hydroxide slurry generated in the seawater magnesia manufacturing process to prepare a precipitate improver of the present invention. The activation treatment is to obtain a reaction rate by increasing the specific surface area when the slurry is granulated, and is obtained by controlling the conditions of the vacuum forming process and the drying process.

First, the magnesium hydroxide slurry (hereinafter referred to simply as 'magnesium hydroxide slurry') generated in the seawater magnesium production process according to the present invention is dewatered, and the dehydration at this time is preferably such that the water content of the slurry is 28-32%. . This is because the water content of the slurry must satisfy this range for the best formability. If the water content of the slurry is less than 28%, it may be difficult to mold, and if it is more than 32%, it may be difficult to form micropores in the vacuum forming process. If the water content cannot be controlled within 32% due to dehydration, it is possible to adjust the control range through drying.

Magnesium hydroxide slurry having appropriate moisture content is molded in a vacuum molding machine. Vacuum molding is a technique for increasing the specific surface area of moldings by forming micropores, that is, a kind of fine cracks in moldings, and is used in the manufacture of ceramic filters, which are components of water purifiers. In the present invention, the dehydrated slurry is preferably formed at a vacuum pressure of 6-7 kg / cm 3 to have a desired specific surface area to ensure activity. If the vacuum pressure is less than 6kg / cm3, the formation of micropores on the surface is insufficient to ensure the desired activity. If the vacuum pressure is more than 7kg / cm3, the vacuum pressure is so high that the micropores on the surface are high. It is difficult to secure the desired activity due to less internal pores.

When forming in vacuum, the particle size is preferably 2-10 mm. This particle size is roughly 1.5-2.0 g / cm2 in apparent apparent density. If the particle size is smaller than 2mm, it is difficult to dissolve before approaching the bottom of seawater or river, and it is difficult to induce a direct reaction with the precipitate. There is a problem that takes too much time to dissolve.

Drying the shaped particles to the appropriate size, the drying conditions also directly affect the activity. Drying conditions are 60-180 minutes at the temperature of 100-180 ℃, if the drying temperature is less than 100 ℃ or drying time is longer than 180 minutes, the drying time is longer, the production cost increases, the drying temperature is higher than 180 ℃ Magnesium and calcium, which are hydroxides, are decomposed into oxides (MgO, CaO), which prevents the removal of harmful substances in water.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Conventional sediment improvers magnesium hydroxide, clay soil material, quicklime and sediment improving agent of the present invention (calcium hydroxide of activity 150: 3% by weight, water-soluble iron: 1% by weight, magnesium hydroxide of activity 90: 90% by weight and other unavoidable impurities ) Was contacted with seawater as shown in FIG. 1 to investigate the chemical composition of the seawater, the change in appearance and the amount of undissolved substances remaining in the sample dish, and the results are shown in Table 2. The weight change and chemical composition of the sample were taken out after 7 days for chemical analysis. After standing, the product was analyzed by X-ray diffraction analysis, Mg, Ca for chelate titration, and SO4 for barium chromate colorimetric method.

sample Upper tissue analysis Chemical composition Sample Residue (%) 10 days 20 days 30 days Invention Powder Mg ²⁺ , Ca ²⁺ 5 0 0 Conventional Magnesium hydroxide Figurine-Figurine Mg (OH) ₂ , CaCO ₃ 40 35 35 Goto system Bed-plate, couch Mg (OH) ₂ , CaCO ₃ , CaSO ₄ 2H ₂ O 40 45 45 quicklime Figurine-Figurine CaCO ₃ , CaSO ₄ , 2H ₂ O 30 35 35

As can be seen from Table 2, the present invention is an active ingredient and reacts within a short period of time, so that the undissolved substance remaining in the same 30 days remains, whereas the conventional improver is a platelet or granular membrane. It remains even later, killing benthic creatures and ruining fisheries.

Example 2

By adjusting the mixing ratio of the calcium hydroxide of activity 150 and the magnesium hydroxide of activity 90 as shown in Table 2 below, the weight change of the precipitate was examined. At this time, the water-soluble iron was 3%, the rest were other unavoidable impurities. The change in weight of the precipitate was tested for the precipitate having a T-S content of 1.52 ppm.

division One 2 3 4 5 6 Magnesium hydroxide content (% by weight) 80 85 90 93 95 98 Calcium hydroxide content (% by weight) 10 5 3 3.5 4 One Sediment weight 5.2 4.9 4.5 4.4 4.25 4.10

As can be seen from Table 3, when the amount of calcium hydroxide is less than 5% by weight it can be seen that the amount of precipitate is less.

Example 3

In the precipitate improver composed of 3% by weight of calcium hydroxide, 1% by weight of water-soluble iron, 90% by weight of magnesium hydroxide and the rest of the unavoidable impurities, the T-S changes in the precipitates with the changes in the activity of calcium hydroxide and magnesium hydroxide were investigated.

division One 2 3 4 5 6 Calcium Hydroxide Activity - 100 150 200 250 300 Activity of Magnesium Hydroxide - 70 90 100 120 150 Amount of T-S in the precipitate (ppm) 1.52 1.49 1.49 1.50 1.51 1.51 Vacuum forming condition and drying condition 7kg / cm3-100 ℃ × 180 minutes 7kg / cm3-150 ℃ × 100 minutes 7kg / cm3-180 ℃ × 60 minutes 9kg / cm3-200 ℃ × 50 minutes 9kg / cm3-250 ℃ × 40 minutes

As can be seen from Table 4, it can be seen that the T-S change in the precipitate increases when the calcium hydroxide activity is 1200 or less and the magnesium hydroxide activity is 100 or less.

Example 4

The sediment improver of the present invention was sprayed on the actual sea water field (depth of 10 m) to show the environmental impact change and the chemical change of the water quality in Table 5. At this time, the precipitate improving agent used was magnesium hydroxide having an activation degree of 90: 90% by weight, calcium hydroxide having an activation degree of 150: 3% by weight, water-soluble iron: 3% by weight, and used as an inevitable impurity. The precipitate improver is to dehydrate the magnesium hydroxide slurry and then to form cylindrical particles 5 mm in diameter and 10 mm in length at a vacuum pressure of 7 kg / cm 3 and dried at 150 ° C. for 100 minutes.

division Spray amount (g / ㎡) Bottom layer Accumulated T-S (ppm) Temperature (℃) DO (ppm) pH Invention Before spraying 200 21.1 4.20 6.79 1.52 40 days after spraying 24.8 4.32 8.50 1.00 55 days after spraying 28.3 5.40 9.51 0.52 Goto system Before spraying 200 21.1 4.20 6.79 1.52 40 days after spraying 24.8 4.11 7.01 1.49 55 days after spraying 28.3 4.10 7.11 1.35 quicklime Before spraying 800 21.1 4.20 6.79 1.52 40 days after spraying 24.8 4.59 9.20 1.35 55 days after spraying 28.3 4.80 8.21 1.62 Control zone (no sediment improver applied) Before spraying Do not spray 21.1 4.20 6.79 1.52 40 days after spraying 24.8 4.10 6.72 1.50 55 days after spraying 28.3 4.05 6.70 1.53

As can be seen from Table 5, the present invention has no detrimental effect on the environment, rather it purifies the water quality of the bottom layer and shows that the sulfides of the deposits (TS: Total Sulfur, indicating pollution measure) decrease with time. .

As described above, since the present invention does not form a film on the bottom surface of a coastal fishery, a river or a lake, there is no death of aquatic organisms living in the bottom, and the accumulation of the bottom removes contaminants due to decay and purifies the water quality. It is effective. It is a feature of the manufacturing method that can continuously exert the green algae or red tide preventive effect and have the activation of the components of the improver to exert such an effect.

Claims (6)

Active calcium hydroxide with an activity of 200 or less: 5% by weight or less, water-soluble iron: 0.1-1% by weight, a precipitate improving material composed of active magnesium hydroxide and other unavoidable impurities having a remaining activity of 100 or less. Dehydrating the magnesium hydroxide slurry generated in the seawater magnesium production process; Vacuum molding the dehydrated raw material into particles; Drying the molded particles; Method of producing a precipitate improver comprising a. 3. The method of claim 2, wherein the dehydration is a water content of the slurry of 28-32%. 3. The method of claim 2, wherein the vacuum forming is performed at a vacuum pressure of 6-7 kg / cm < 3 >. The method of claim 2, wherein the vacuum forming is characterized in that the particle size of 2-10mm. The method of claim 2, wherein the drying is performed for 60-180 minutes at a temperature of 100-180 ℃.