KR100502235B1 - A preparation method of treatment liquid for decarbonizing sea water having low contents-silica slag solution - Google Patents

Abstract

The present invention relates to a method for producing a treatment solution for desalination of seawater having a low silica content, the composition of which

In manufacturing seawater magnesia through decarbonation process and magnesium hydroxide precipitation process in seawater,

The decarbonation process is performed by using a slag eluate prepared by crushing slag to 45 μm or less, injecting water, adjusting the pH to 11.5 to 11.8, and then filtering the slag. There is provided a method of preparing the same.

According to the present invention, by producing a decarbonated material having a much lower silica content than the conventionally used calcined lime based materials as seawater decarboxylates, at least the silica content acting as an impurity in the calcium carbonate sludge produced during the decarboxylation treatment is reduced. Can be.

Description

TECHNICAL FIELD OF THE INVENTION A process for producing a desalination solution for seawater with low silica content {A PREPARATION METHOD OF TREATMENT LIQUID FOR DECARBONIZING SEA WATER HAVING LOW CONTENTS-SILICA SLAG SOLUTION}

The present invention relates to a method for preparing a seawater decarbonation treatment liquid having a low silica content, and more particularly, to a method for producing a slag eluate for decarbonation having a low silica content using slag as a by-product of steel mill in seawater for seawater magnesia production. will be.

The oxide produced by extracting magnesium ions from seawater is called seawater magnesia and is mainly used as a refractory material. The seawater magnesia manufacturing process includes a step of removing bicarbonate ions or sulfate ions contained in seawater in advance in order to lower the calcium oxide concentration in the magnesia. This step is called the decarbonation process of seawater, and calcareous oil is currently used to remove the bicarbonate and sulfate ions (Refr. Jour., 28, 302-307 (1952), refractory engineering, Gibo-dang ( 1962).

The calcined lime oil is prepared by reacting quicklime produced by calcining limestone with water. During this process, a significant amount of silica contained in limestone is separated in the separation process of sieving microporous limestone, but fine silica is not separated. It passes through the sieve and remains in the slaked lime oil.

As a result, since the residual silica is included in the sludge produced in the seawater decarbonation process, a problem arises in that the content of silica, which is an impurity component that obstructs the utilization of the decarbonated sludge, becomes high.

Therefore, there is a demand for developing a decarbonated material having a low silica content or developing a technology that does not precipitate during the decarbonated reaction even if a silica component is present.

On the other hand, most of the limestone produced in Korea is composed of CaO: 50 ~ 53% and SiO ₂ : 1.5 ~ 5%. When calcined limestone with a high SiO ₂ content is added to water, calcined lime oil is made, and most of the SiO ₂ enters the lime lime oil as it is.

Therefore, even in the process of refining calcined lime oil to remove the unbaked limestone particles, SiO _2, etc. in order to be applied to the decarbonation process of seawater, it contains a significant amount of SiO ₂ .

That is, generally, the larger particles in the pulverized limestone oil are called crude oil and the smaller particles are refined oil, but crude oil is used in the decarbonation process of seawater. Such crude oil contains about 0.22% of SiO ₂ , that is, about 2200 ppm.

Therefore, when the crude oil and the seawater are reacted to perform the decarbonation process, when Ca (OH) ₂ in the crude oil is precipitated as CaCO ₃ , about 2200 ppm SiO ₂ contained in the crude oil is precipitated together in the CaCO ₃ precipitate formed. As a result, the recycling of CaCO ₃ causes serious problems as impurities.

Accordingly, an object of the present invention is to provide a method for producing a seawater decarbonate treatment liquid having a very low SiO ₂ content by using slag which is a by-product discharged from a steel mill.

According to the invention,

In manufacturing seawater magnesia through decarbonation process and magnesium hydroxide precipitation process in seawater,

The decarbonation process is performed by using a slag eluate prepared by crushing slag to 45 μm or less, injecting water, adjusting the pH to 11.5 to 11.8, and then filtering the slag. There is provided a method of preparing the same.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The inventors of the present invention found that the main components of slag generated in steel mills are CaO, SiO ₂ , iron oxide, and other components, including MgO and Al ₂ O ₃ , and the base is also one or more. Paying attention to the fact that the components are eluted to form a solution having a high pH, an appropriate slag is selected, and these are immersed in water. _{2 the} content was found to be significantly reduced compared to the current process and the present invention was completed.

Slags usable in the present invention are those discharged as by-products from steel mills, blast furnace slag, converter slag, molten iron preliminary slag, stainless slag, furnace slag (oxidizer slag, reducing machine slag), ladle slag For example, converter slag, furnace oxidizer slag, and dephosphorized slag among molten iron preliminary slag are used.

This will be a selection of the slag are eluted Ca as much as possible, if it contains a lot of Al ⁺³ component is presented Al ⁺³ ions are eluted in the leaching solution slag consequently acts so as impurity components in the decarboxylation in the present invention, the sludge in the slag, As such, it is preferable to use a converter slag having a high basicity and a large amount of slag which is highly eluted with Ca ⁺² , an electrolytic oxidizer slag, and a dephosphorized slag in the molten iron preliminary slag.

For example, in the case of converter slag, the content of Al ₂ O ₃ is 3% or less, so that the Al ^{+ 3} is not eluted even if eluted in a later process.

The slag is pulverized to 45 μm or less. Although the elution process can proceed later even if it is more than 45㎛, when less than 45㎛ is eluted more quickly and when the reaction of slag and water to produce the slag eluate, the amount of water compared to the granulated slag easily meet the desired pH range easily It is preferable to grind to 45 micrometers or less as it may.

Thus, the appropriate slag is pulverized to 45㎛ or less and then adjusted to pH range of 11.5 ~ 11.8 while injecting water and filtered to obtain an eluate. At this time, even if the pH range is 11.5 or less, there is no big problem, but the content of Si in the eluate is increased, which does not meet the purpose of achieving the low silica content of the present invention. Since the amount of the reactant used to reduce is reduced as a result the amount of eluate is reduced is undesirable.

In addition, since Si ⁺² contained in the eluate does not have a significant effect on the SiO ₂ content present as impurities in the decarbonated sludge between pH 11.5 and 11.8, the pH of the eluate is preferably adjusted to 11.5 to 11.8.

In other words, the Si in the eluate is lowered at pH 12 or higher, but it must go through the seawater decarbonation process, so when the pH is adjusted to 11.5 to 11.8, the present Si is dissolved and does not need to be excessively increased to pH 12 or higher.

Therefore, if the Si content is adjusted by adjusting the pH to 11.5 to 11.8, it does not precipitate during the decarbonation reaction and thus does not significantly affect the SiO ₂ content present as impurities in the decarbonate sludge.

The present invention has an advantage of lowering the Si concentration contained in the eluate by appropriately adjusting the pH of the eluate when preparing the eluate from the crushed slag. Once the Si ⁺⁴ content in the eluate is lowered, even when decarbonated seawater for seawater magnesia production is present in dissolved state in the decarbonation reaction solution and hardly precipitated, consequently, the SiO ₂ content in the decarbonated sludge is lowered. will be.

For reference, when decarbonated seawater for seawater magnesia production using the eluate thus prepared, the reaction may be performed at a pH of 9 to 9.5 to reduce the loss of magnesium ions in the seawater.

Hereinafter, the present invention will be described in detail through examples, which are intended to illustrate the present invention and are not intended to limit the present invention.

<Example 1>

First, the converter slag was pulverized to 45 μm or less, and water was injected until the pH of the reactant was 11.5, followed by filtration using general filter paper to prepare an eluate.

The eluate prepared as described above was added to a beaker containing 1 liter of seawater, adjusted to pH 9 to perform a decarbonation reaction.

As described above, the dewatered reaction of seawater was carried out, and the produced sludge was separated and dried, and the SiO ₂ content was analyzed by a general mineral analysis method. The results are shown in Table 1 below. On the other hand, for comparison, the SiO ₂ content measured in the sludge generated in the plant performing decarbonation using the actual crude oil is shown in Table 1 together.

Decarbonated Material SiO ₂ content in weight of sludge Slag eluate prepared according to the present invention 0.3 to 0.5 Current formula 8 to 10

As shown in the above table, when the slag eluate of the present invention was used as the decarbonated material, it was confirmed that the SiO ₂ content contained in the sludge was further reduced.

<Example 2>

This example is an experiment for deriving the appropriate crushed particle diameter of slag.

The same experiment as in Example 1 was repeated except that the grinding particle diameter and distilled water input amount were changed as described in Table 2, and the observed pH values were shown together in Table 2 below.

Distilled Water Input Slag crushed particle size pH condition Distilled water 500cc Distilled water 400cc Distilled Water 300cc Distilled water 200cc Distilled water 100cc 50cc distilled water Distilled water 30cc Less than 45㎛ 11.68 11.63 11.82 11.78 11.8 12.14 12.32 0.25-0.5mm 10.51 11 11.12 11.3 11.37 11.54 11.91 0.5-1mm 10.48 10.76 10.83 10.87 10.98 11.34 11.81 1 to 2 mm 10.36 10.54 10.84 10.86 11 11.14 11.69 2.36-3.35mm 10.15 10.33 10.55 10.67 10.72 10.91 11.34

As can be seen from Table 2, when the crushed particle diameter of the slag is 45㎛ or less, even if the input amount of distilled water compared to the granulated slag can satisfy the desired pH range of 500cc, there is an advantage that the production amount of the eluate can be increased at a time.

delete

<Example 3>

This example is an experiment for deriving a proper pH of a reactant that can effectively elute Si ions from slag.

 The pH tester was mounted in the beaker of Example 1, and then the amount of water injected was changed to change the pH of the reactants to the values shown in Table 3, and the same experiment as in Example 1 was repeated. 3 is shown together.

Eluent pH 11.18 11.23 11.31 11.36 11.42 11.51 11.64 11.80 11.91 Si content (ppm) 19 21 21 21 19 18 14 8 6.5

  As shown in the above table, when the pH of the eluate was 11.5 or more, it was confirmed that the content of Si ion in the eluate began to decrease, and when the pH was 11.80, it was confirmed that the Si ion content was reduced to 8 ppm.

On the contrary, since the concentration of SiO _{2 in the} crude oil contained 2200 ppm, according to the method of the present invention, the concentration of Si in the eluate could be remarkably reduced by appropriately adjusting the pH of the eluate from the ground slag.

According to the above, SiO ₂ in the sludge produced after the decarbonation process by using an eluate having a low silica concentration as a decarbonation treatment solution of seawater obtained by appropriately adjusting the pH by using slag containing less aluminum oxide in the steelworks-generated slag. The content can be significantly reduced.

Claims (2)

In manufacturing seawater magnesia through decarbonation process and magnesium hydroxide precipitation process in seawater, The decarbonation process is performed by using a slag eluate prepared by crushing slag to 45 μm or less, injecting water, adjusting the pH to 11.5 to 11.8, and then filtering the slag. Manufacturing method The method of claim 1, wherein the slag is selected from a converter slag consisting of CaO, SiO ₂ , iron oxide and MgO as an auxiliary component, an electric furnace oxidizer slag and a dephosphorized slag.