KR101468986B1 - Purification method of limestone for preparing high purity calcium solution - Google Patents

Abstract

The present invention relates to a method for purifying limestone for the preparation of a high purity calcium solution, and more particularly to a method for purifying limestone comprising: crushing and crushing low-grade limestone having an impurity content of 0.4 to 0.8% by weight and a loss on ignition of 42 to 44% And stirring the crushed and ground limestone with 2 to 10 M of nitric acid, followed by filtration and solid-liquid separation. The present invention also relates to a method for purifying limestone for producing a high purity calcium solution.

Description

Technical Field [0001] The present invention relates to a method for purifying limestone for preparing high purity calcium solution,

The present invention relates to a method for purifying limestone for the production of a high purity calcium solution.

In general, the limestone which is calculated in the country (Calcite, CaCO ₃₎ is dolomite _{(Dolomite, CaMg (CO 3)} 2), Muscovite _{(Muscovite, KAl 2 (Si 3} Al)) 10 (OH, F) 2) and quartz (Quartz , And SiO ₂ ), which are not only poor in purity but also poor in basic properties of raw materials such as low activity and unevenness in particle size, and can be used as raw materials or additives in high-quality veneering and high value-added industries such as environment and fine chemical processing It is not applicable.

On the other hand, a variety of calcium solutions can be produced from limestone. Among them, the hydrate of calcium nitrate (Ca (NO ₃ ) ₂ ) is a colorless monoclinic crystal, which dissolves in crystal water at 42.7 ° C and becomes an anhydrous at 100 ° C or higher . These calcium solutions are mainly used for the production of nitrates, softening, dyeing agents, refrigerant solvents, detergents, cement admixtures, oxidizing agents and the like, and also as fast-acting fertilizers. Particularly, calcium nitrate as a fertilizer is also called nitrate lime and is a physiological basic fertilizer. Since it is very strong in absorbency, it has not been widely used in the prior art.

Therefore, in order to produce the calcium solution having the above-mentioned usefulness, it has been conventionally manufactured by a process of neutralization, filtration, concentration under reduced pressure, crystallization, dehydration, etc. However, in order to perform the above- And the problem is that excessive workforce input causes a decrease in workability and an increase in product unit price. In particular, the vacuum concentration process is relatively large in its peripheral devices, so that not only difficult installation but also a wider occupied space is required. In addition, the above-described reduced-pressure concentration process causes excessive power consumption, and there is a problem in that it is not easy to produce a high-purity calcium solution.

The prior art related to the present invention is Korean Patent Laid-Open No. 10-2004-0069754 (entitled " Method for producing liquid calcium chloride using shells, "

Accordingly, it is an object of the present invention to provide a method for purifying limestone which can easily produce a high-purity calcium solution in an efficient and simple manner.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be understood by those skilled in the art from the following description.

In order to solve the above problems, the present invention provides a method for producing a limestone, which comprises crushing and crushing low-grade limestone having an impurity content of 0.4 to 0.8% by weight and a loss on ignition of 42 to 44% by weight based on the total limestone weight; And

Mixing the crushed and ground limestone with 2 to 10 M of nitric acid, and then filtering and solid-liquid separating the limestone.

At this time, the impurity is characterized in that it comprises at least one member selected from the group consisting of _{SiO 2, Al 2 O 3,} Fe 2 O 3 and MgO.

Stirring of the crushed and ground limestone and nitric acid is carried out for 5 to 15 minutes.

The dissolution rate of limestone to nitric acid after the stirring is 98 to 99%.

The solid separated by solid-liquid separation includes quartz and muscovite.

Further, the crushing is performed with a jaw crusher and a cone crusher.

Characterized in that the pulverization of the crushed low-grade limestone is carried out by a pulverizer.

According to the present invention, a calcium solution can be easily and easily prepared by refining limestone with a simple and efficient method using strong acid, and in particular, it is possible to use a cheap nitric acid among strong acids, thereby reducing the processing cost.

In addition, the purification method of the present invention can be usefully used for manufacturing calcium products and calcium compounds for medicines and medicines which require high purity calcium because of high purity of the calcium solution.

1 is a flowchart showing a method of purifying limestone for producing a high purity calcium solution according to a preferred embodiment of the present invention.
2 shows a scanning electron microscope (SEM) photograph (FIG. 2 (a)), an energy dispersive spectroscopy (EDS) result (FIG. 2 (b)), and a mapping result (FIG. 2 (c) to be.
3 is a photograph of a solid separated after filtration in Examples 1 to 5 and Comparative Example 1 according to the present invention.
FIG. 4 shows X-ray diffraction (XRD) analysis results of solids separated after filtration in Examples 1 to 5 and Comparative Example 1 according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention relates to a process for crushing and crushing low-grade limestone having an impurity content of 0.4 to 0.8% by weight and a loss on ignition of 42 to 44% by weight based on the total limestone weight; And

Mixing the crushed and ground limestone with 2 to 10 M of nitric acid, and then filtering and solid-liquid separating the limestone.

1 is a flowchart showing a method of purifying limestone for producing a high purity calcium solution according to the present invention. The present invention will be described in detail with reference to Fig.

S10 : Low-grade  Crushing and crushing limestone

The method for purifying limestone for the preparation of a high purity calcium solution according to the present invention comprises a step (S10) of crushing and crushing low-grade limestone having an impurity content of 0.4 to 0.8% by weight and a loss on ignition of 42 to 44% by weight based on the total weight of limestone .

For specific examples of low-grade limestone, see Table 1 and Table 2 below.

Table 1 shows the results of analysis of the components and contents of limestone by X-ray fluorescence (XRF).

ingredient SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO Weight loss content(%) 0.13 0.03 0.11 55.70 0.59 43.34

Referring to Table 1, limestone includes impurities such as SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ and MgO.

The crushing of the low limestone may be performed with a jaw crusher and a cone crusher.

The crushed limestone is crushed, the crushed can be carried out with a pulverizer, and the crushed and crushed limestone can have a size of 3 mm or less. When the size of the crushed and ground limestone exceeds 3 mm, the strong acid and limestone are dissolved, and the reaction time is prolonged. In addition to the limestone, the impurity minerals are not completely separated. Therefore, the solubility in strong acid decreases, I can not.

S20 : Crushed and ground limestone with nitric acid Agitated  Filtration and solid-liquid separation

Next, the method for purifying limestone for producing a high purity calcium solution according to the present invention comprises the step (S20) of stirring the crushed and ground limestone with 2 to 10 M of nitric acid, followed by filtration and solid-liquid separation.

At this time, the concentration of the nitric acid may be 1 to 10 M, but 2 to 10 M in which the dissolution rate of limestone is 98 to 99% is more suitable. When the concentration of nitric acid is less than 1 M, the limestone can not be completely dissolved. When the concentration exceeds 10 M, the concentration of strong acid is high, so that the limestone is dissolved and then the solid-liquid separation is not performed.

In addition, limestone can be included in a mixing ratio (g / L) of 50 to 500 to the total volume of strong acid. When the mixing ratio is less than 50 g / L in the concentration range of 1 M to 10 M of nitric acid and at the low concentration of 1 M, the amount of strong acid required to dissolve the limestone is excessively added to lower the economical efficiency. g / L, the amount of strong acid required to dissolve the limestone is insufficient, so that the limestone can not be completely dissolved. Also, since the water content is low in the mixture of limestone and strong acid, solid-liquid separation may be difficult. More specifically, when the amount of limestone added to the nitric acid (volume) is 50 to 500 g, the amount of limestone that can be dissolved in nitric acid from the minimum to the maximum is set. That is, 50 g is the maximum amount that can be dissolved in the lowest concentration (1 M) of nitric acid, and therefore, in the case of less than 50 g, the acid required for dissolving nitric acid in the limestone remains. In addition, 500 g is the maximum amount of nitric acid that can be dissolved at the highest concentration (10M), and when it exceeds 500 g, limestone remains because of insufficient melting acid. In case of melting more than 500 g, 10 M of strong acid is almost pure 60% of nitric acid, so there is almost no water. After the reaction with limestone, the viscosity (stickiness and fluidity) of the liquid becomes high and the filter (filtration) becomes impossible .

Agitation of the crushed and ground limestone and nitric acid can be carried out for 5 to 15 minutes. When the agitation is performed for less than 5 minutes, the limestone and nitric acid are not sufficiently mixed, so that the dissolution rate of limestone to nitric acid is lowered and the purification efficiency of limestone may be lowered. And not more than 15 minutes in terms of process efficiency.

Through the filtration, limestone dissolved in nitric acid and solid filtered by a filter can be solid-liquid separated. The filtration may be filtered by a membrane filter, but is not limited thereto.

After stirring the crushed and ground limestone and nitric acid, the dissolution rate of limestone to nitric acid may be 98-99%. In the method for purifying limestone for producing a high purity calcium solution according to the present invention, the dissolution rate of limestone can be controlled by the concentration of nitric acid, and 98 to 99% of limestone can be dissolved in the nitric acid concentration of 2 to 10M.

Example 1: Purification of low grade limestone 1

The limestone was crushed using a jaw crusher and a cone crusher, and the crushed limestone was crushed using a pulverizer. Crushed and pulverized limestone had a size distribution of less than 3 mm.

100 g of the pulverized limestone and 1000 mL of nitric acid were stirred for 10 minutes, at which time the nitric acid concentration was 1M. The mixture of limestone and nitric acid was filtered and then subjected to solid-liquid separation to purify the low-grade limestone.

2 shows a scanning electron microscope (SEM) photograph (FIG. 2 (a)), an energy dispersive spectroscopy (EDS) result (FIG. 2 (b) ).

Referring to FIG. 2, limestone is present as CaCO ₃ in the same manner as in the XRF analysis of Table 1, but it can be seen from the EDS result that impurities having Al and Si components are present, and this impurity is muscovite, KAl ₂ (Si ₃ Al)) ₁₀ (OH, F) ₂ ).

Example 2: Purification of low-grade limestone 2

The low-grade limestone was purified in the same manner as in Example 1 except that the concentration of nitric acid was 2M each.

Example 3: Purification of low-grade limestone 3

The low-grade limestone was purified in the same manner as in Example 1 except that the concentration of nitric acid was 3M each.

Example 4: Purification of low grade limestone 4

The low-grade limestone was purified in the same manner as in Example 1 except that the concentration of nitric acid was 5M each.

Example 5: Purification of low-grade limestone 5

The low-grade limestone was purified in the same manner as in Example 1 except that 500 g of pulverized and ground limestone was mixed with 10 M phosphorous nitrate.

Comparative Example 1

The low-grade limestone was purified in the same manner as in Example 1, except that 550 g of crushed and ground limestone was mixed with 11 M of nitric acid.

Experimental Example 1: Analysis of dissolution rate of limestone according to nitric acid concentration

In order to determine the degree of dissolution of limestone according to the concentration of nitric acid in the purification method of limestone for producing a high purity calcium solution according to the present invention, the solid was separated by filtration and solid-liquid separation and analyzed by X-ray diffraction (XRD) The results are shown in Table 2, Fig. 3 and Fig.

Yes Mixing ratio
(g / L) HNO ₃ concentration
(M) Amount of residue
(g) Dissolution rate
(%) Example 1 100 One 51.5036 49.64 Example 2 100 2 1.7334 98.27 Example 3 100 3 0.2032 99.80 Example 4 100 5 0.1763 99.82 Example 5 500 10 7.7670 98.45 Comparative Example 1 550 11 - -

As shown in Table 2, in Examples 1, 2 and 5 and Comparative Example 1, the maximum amount of dissolution was determined by reacting nitric acid with limestone. In Example 1, about 50 g of residue remained, It can be seen that there is a large amount of undissolved limestone. In Example 2, the dissolution rate was about 98%, indicating that most of the limestone was dissolved. In Example 5, it was found that most limestone was dissolved at a dissolution rate of 98% by reacting 500 g at a concentration of 10 M of nitric acid. On the other hand, in Comparative Example 1, when 550 g of nitric acid was dissolved, the content of water was low due to the high concentration of nitric acid, so that solid-liquid separation was not obtained.

On the other hand, in Examples 3 and 4, when the addition amount of limestone was fixed at 100 g, only the concentration of nitric acid was changed, and the maximum dissolution rate was examined. As a result, the dissolution rate was 99%, indicating that limestone was completely dissolved.

3 (a) is a photograph of the residue after the filtration process of Example 1 (nitric acid concentration 1M), (b) is a photograph of the residue after the filtration process of Example 2 (nitric acid concentration 2M) (c) is a photograph of the residue after the filtration step of Example 3 (nitric acid concentration 3M), (d) is a photograph of the residue after the filtration step of Example 4 (nitric acid concentration 5M) (Concentration of nitric acid: 10M). (f) is a photograph of Comparative Example 1.

As shown in FIG. 4, calcite, CaCO ₃ and dolomite and CaMg (CO ₃ ) ₂ were mainly present in a, and calcite, dolomite and muscovite (KAl _{2 3} Al)) ₁₀ (OH, F) ₂ ) and quartz (SiO ₂ ). In c and d, only muscovite and quartz are present, and when the concentration of nitric acid is 3 to 5M, both calcite and dolomite are dissolved in nitric acid. In addition, in e, some calcite, dolomite, muscovite and quartz remain, showing the maximum addition amount of limestone capable of dissolving in strong acid 10M with a dissolution rate of about 98%. On the other hand, only muscovite and quartz were detected as impurities in f, but solid - liquid separation was not completely achieved. Therefore, it is also possible to dissolve at least 98% of limestone by setting the concentration of strong acid to 2 to 10M. The above-mentioned "a" to "f" each show (a) to (f) in FIG.

Although a specific embodiment of the method of purifying limestone for producing a high purity calcium solution according to the present invention has been described above, it is apparent that various modifications can be made without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

Claims (7)

Crushing and grinding low-grade limestone having an impurity content of 0.4 to 0.8% by weight and a loss on ignition of 42 to 44% by weight with respect to the total limestone weight; And
Agitating the crushed and ground limestone with 3 to 5 M of nitric acid, and filtering and solid-liquid separating the limestone,
Wherein the limestone is mixed at a mixing ratio (g / L) of 100 to the total volume of nitric acid to dissolve the limestone at a dissolution rate of 99%.
The method according to claim 1,
The impurity is _{SiO 2, Al 2 O 3,} Fe 2 O 3 and a method for purification of high-purity limestone calcium solution prepared comprising the MgO 1 or more selected from the group consisting of.
The method according to claim 1,
Wherein the stirring is performed for 5 to 15 minutes.
delete The method according to claim 1,
Wherein the solid separated by solid-liquid separation comprises quartz and muscovite.
The method according to claim 1,
Wherein said crushing is performed with a jaw crusher and a cone crusher.
The method according to claim 1,
Characterized in that the pulverization is carried out in a pulverizer.

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