JPH02279504A - Production of zirconium oxychloride - Google Patents

Abstract

PURPOSE:To obtain high-purity zirconium oxychloride at a low cost by an ordinary industrial process by treating the product obtained by melting zircon sand and a CaO-contg. raw material with hydrochloric acid in two stages and the with calcium chloride. CONSTITUTION:A mixture contg. zircon sand and the CaO-contg. raw material in >=2.5, or preferably 2.8 to 4, molar ratio of CaO/ZrO2 is heated to 1500 to 2600 deg.C and melted, and then the molten product is quenched by water granulation, etc. The acid-soluble product thus obtained is pulverized to the powder having <=150mu grain size, the powder is brought into contact with dil. hydrochloric acid to selectively elute and separate the calcium silicate component, the concentrated CaZrO3 as the elution residue is recovered, and the residue is catalytically dissolved by concd. hydrochloric acid to recover a Zr decoction. In this case, the residue is advantageously eluted by the hydrochloric acid having <2mol/l concn. in the slurry and then with the hydrochloric acid having >=2mol/l concn. CaCl2 is then added to the Zr decoction to deposit zirconium oxychloride crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a method for producing high-purity zirconium oxychloride, which is used as a starting material for producing zirconium compounds.

[Prior art] Zirconia can be used as a raw material for sintered materials such as ferroelectric materials, piezoelectric materials, catalyst carriers, solid polymers, heat insulating materials, heat-resistant materials, anti-tension materials, abrasive materials, etc.
It is also used in a wide range of fields such as optical glass additives, thermal spraying materials, and M benefits.

In recent years, as research and development related to fine ceramics has become more active, the excellent physical properties of zirconia ceramics have attracted attention, and their use as high-performance electronic ceramic materials, high-strength, high-toughness ceramic materials, etc. is expanding.
Demand for high-quality zirconia fine powder, which is a raw material for these products, is increasing.

A general method for producing high-purity zirconia for use in fine ceramics is to use zirconium salts such as zirconium oxychloride and zirconium sulfate as starting materials, and to process aqueous solutions of these salts through neutralization or hydrolysis reactions. A method has been adopted in which a precipitate of zirconium hydroxide or hydrate is generated, which is then dehydrated, dried, and calcined. A specific method is to add an alkali such as aqueous ammonia to an aqueous solution of zirconium oxychloride, neutralize it to produce hydroxide, filter it, wash it, dry it, and then sinter it. It is being said.

However, in this method, when neutralizing with alkali to produce a precipitate of zirconium hydroxide, Fe, Al, and T, which are present as impurities in zirconium oxychloride, are
Since hydroxides such as i, Si, etc. are mixed into the zirconium precipitate, purified raw materials must be used, and zirconium oxychloride, which has been repeatedly recrystallized to remove impurities, is usually used as a starting material. It is used as.

Zirconium oxychloride is not only a raw material for manufacturing zirconia powder for fine ceramics, but also an important raw material for manufacturing zirconium compounds for optical glasses, oxygen sensors, piezoelectric elements, chemicals, etc. In terms of quality, Higher purity is required.

Normally, zirconium oxychloride is produced by melting zircon sand in an alkali together with caustic soda, washing the melt with water, dissolving and separating sodium zirconate with hydrochloric acid, and then concentrating the solution after separating and removing insoluble matter. It is manufactured by precipitating zirconium chloride crystals.

Further, an aqueous zirconium oxychloride solution is produced by a method such as hydrolyzing zirconium tetrachloride with water or dissolving zirconium carbonate in hydrochloric acid.

[Problems to be Solved by the Invention] In the production method described above, zirconium oxychloride obtained by the caustic soda dissolution method usually contains a large amount of impurities, and unless the impurities are removed by repeated recrystallization, it cannot be used for fine ceramics or It cannot be used as a raw material for producing other high-purity zirconia compounds, and a large amount of cost is required to obtain high-purity zirconia oxychloride.

The present invention overcomes the drawbacks of the prior art as described above, and enables industrially advantageous production of zirconium oxychloride with low impurity content as a raw material for producing fine ceramics and various other zirconium compounds through normal industrial operations. In particular, it is characterized by providing a method for preparing Si, T in zirconium oxychloride, which has been difficult with conventional techniques.
The content of impurities such as i, Ae, and Fe is 100 p each.
It is an object of the present invention to provide a method for producing high-purity zirconium oxychloride in which the purity is reduced to 111 or less.

[Means and effects for solving the problem] The present inventors
As a result of intensive research to solve the drawbacks of conventional methods, we mixed zircon sand with a calcium source such as lime, quenched it by electrolysis, and leached the resulting zirconium-containing product with hydrochloric acid.
The soluble substances mainly composed of calcium silicate were separated, and the insoluble substances mainly composed of calcium zirconate were further eluted with hydrochloric acid, and the insoluble substances were separated and removed. Calcium chloride was added to the obtained zirconium-containing eluate, and oxychloride was added. The present invention was completed based on the discovery that highly pure zirconium oxychloride with low impurity content can be obtained by precipitating zirconium crystals and recovering them.

That is, the present invention includes (a) a melt production step in which a raw material mixture of zircon sand and a CaO-containing raw material is heated and melted, and then rapidly cooled to obtain an acid-soluble molten product.

(b) a step of concentrating the zirconium component by contacting the acid-soluble molten product with a dilute aqueous hydrochloric acid solution to selectively elute and separate the calcium silicate component; (c) contacting and dissolving the zirconium component with concentrated hydrochloric acid to remove the insoluble component; (d) a crystallization separation step of adding calcium chloride to the zirconium leachate to precipitate zirconium oxychloride crystals and separating and recovering the obtained crystals; This is a method for producing zirconium oxychloride.

The present invention will be explained in detail below.

In the method for producing zirconium oxychloride according to the present invention, first, in the melt generation step, a raw material mixture of zircon sand as a starting material and a CaO-containing raw material is heated and melted, and then rapidly cooled to obtain a molten product.

As the raw material zircon sand used in the present invention, a commercially available product can be used as it is, but a pulverization operation may be added if necessary.

In addition, quicklime, slaked lime, various types of calcium carbonate, etc. can be used as CaO-containing raw materials, and if necessary, coarsely crushed
Alternatively, it can be used after being granulated.

In the present invention, the mixing ratio of zircon sand and CaO-containing raw material is important and needs to be determined in consideration of the composition of the molten product. In the present invention, the raw materials are mixed so that the molar ratio of Z'0. It is thought that this reaction follows the reaction shown in 1).

Zr5iO<+3CaO−+CaZr0a+2CaO−
Si02... (1) As shown in the above formula (1), the ratio of zircon sand and quicklime is 3 moles of CaO to 1 mole of Zr0, but in the actual reaction, impurities contained in the raw materials, Since there is some non-uniformity in the raw material mixture, it is desirable that the amount of CaO is 2.5 moles or more, preferably 2.8 to 4 moles, per mole of Zrozl.

Next, the raw material mixture is heated and melted at 1500 to 2600°C, preferably 1700 to 2400°C, and then the molten product is rapidly cooled by pulverization or the like. This operation usually uses an arc furnace equipped with a tap, through which the molten product flows out and is quenched by water pulverization by being blown with a high-pressure water stream. By quenching by water pulverization, the zirconia component in the molten product can be rendered acid-soluble, and quenched amorphous or acid-soluble calcium zirconate ((:aZr○) can be obtained.

According to the research conducted by the present inventors, zircon sand and quicklime were used to melt a mixture of 2.5 mol or more, for example 3 mol, of CaO per 21 mol of Zr0, and the molten product was pulverized and rapidly cooled. In the case, X-ray diffraction analysis shows CaZr0z(J
Only the X-ray diffraction peak of CPDS card 35-790.1985) appears, and 2CaO.Sin is amorphous. On the other hand, when the molten product is gradually cooled, in addition to the X & 11 diffraction peaks of CaZr0z, 0.8
5Zr02・0.15CaO (JCPDS card 26
-341.1976) or ZrO□ (JCPDS Card 17-923.1987) similar X-ray diffraction peaks appear.

On the other hand, when less than 2.5 mol of CaO is mixed and melted with respect to 1 mol of ZrO2, and the molten product is pulverized and rapidly cooled, in addition to CaZrO3, 0.85ZrO, 0.1
A peak similar to 5CaO1 or ZrO2 appears.

Furthermore, when mol of Cm02 is mixed with mol of Zrozl and melted, the quenched product no longer contains CaZ.
The X-ray diffraction peak of rfL did not appear, and the peak was 0.852 rL・
0.15CaO or 7. There are only r02-like peaks.

Here, 0.85Zr02・0.15CaO and ZrO2 show almost similar X-ray diffraction patterns, and in reality, a solid solution of 0 to 0.15 moles of CaO in ZrO2 is produced. It is estimated to be.

Furthermore, the present inventors investigated the solubility (elution) of the zirconia component in hydrochloric acid for various melted products. As a result, X41 diffraction analysis revealed that CaZrO3
It was found that almost 100% of the zirconia component was eluted in the molten product in which only 2 mol/l of hydrochloric acid was present. In contrast, X-ray diffraction analysis revealed that Carry) and 0
．． The melted product in which 85ZrO, .15CaO or ZrO2 was observed is 0.85ZrOz.0, 15C
It was found that the elution rate of the zirconia component decreased as the peak intensity of aO or Z r O2 increased. And there is no diffraction peak of Cdr03 in the melted product.
, 0.852r02・0.15CaO or Z r
In the case of only the Ot diffraction peak, the elution rate of the zirconium component is 50% even when dissolved in 2 to 11 mol/l of hydrochloric acid.
% or less.

Based on the above knowledge, in order to melt a mixture of zircon sand and a CaO-containing raw material and make the zirconia component in the molten product acid-soluble, it is necessary to make the zirconia component in the molten product acid-soluble by X-ray diffraction analysis. It is important to create a composition that yields only Z r 0
2 to 2.5 mol or more, and the molten product was rapidly cooled to 0.852rOz-0.15
It is necessary to prevent the formation of CaO or ZrO2.

The acid-soluble molten product thus obtained is desirably pulverized to a powder having a particle size of 150 μm or less, preferably 100 μm or less.

If the particle size exceeds 150 μm, colloids of SiO2 will aggregate on the particle surface during the next step of elution treatment with dilute hydrochloric acid, resulting in poor elution rate and separation performance.

Next, in the step of concentrating the zirconium component, the calcium zirconate component and the calcium silicate component are selectively eluted and separated from the acid-soluble molten product slurry produced by contacting the acid-soluble molten product with a dilute aqueous hydrochloric acid solution. H(
By performing the elution under conditions where the M concentration is less than 2 mol/l, as much calcium and silica as possible in the acid-soluble molten product can be eluted. The reaction formula is as shown in the following formula (II).

CaZr0z+2CaO・SiO□+4flCf-Ca
ZrOt+ 2CaCI2z+5iOz+2112
0 . Elution is carried out using a hydrochloric acid aqueous solution having a concentration of less than 1 liter, and the calcium zirconate component of the elution residue is separated and recovered.

Next, in a zirconium leaching step, the calcium zirconate obtained in the leaching step is dissolved in contact with concentrated hydrochloric acid to recover a zirconium leaching solution. Calcium zirconate is immersed in concentrated hydrochloric acid solution to remove HC in the slurry.
L: Leaching is performed under conditions where the degree of a is 2 mol/l or more, and the zirconium content is leached out.

Specifically, the following formula (III) CaZrO> + 4H is added to the calcium zirconate content of the elution residue in the step.
CZ-Zr0CL +2H20+ CaCff1i ・
...1 equivalent of HCl in the reaction formula shown by (III)
．． Leaching is carried out using 0 to 1.2 times the amount and at a hydrochloric acid concentration of 2 mol/l or more.

Furthermore, in both the concentration step and the leaching step, there is no particular limitation on the slurry concentration in the eluate or leachate, as long as it satisfies a predetermined hydrochloric acid concentration.

Although there are no particular limitations on the elution or leaching in this case, it seems that the elution or leaching rate is generally faster when heated, and 50 to 100°C is preferable.

In addition, when leaching the acid-soluble molten product with hydrochloric acid,
It is also possible to perform leaching in one step with 2 mol/l or more of hydrochloric acid, but in this case, calcium and silica are also leached together with zirconium into the leaching solution, and the silica that has been dissolved in the leaching solution is hydrated. Decomposition leads to insoluble silica precipitates, making subsequent solid-liquid separation extremely difficult.

Therefore, when leaching an acid-soluble molten product with hydrochloric acid,
As in the present invention, leaching is carried out in advance with less than 2 mol/l of hydrochloric acid to elute as much of the calcyano, silica, and silica content in the molten product as possible, and then the leaching residue is dissolved in 2 mol/l or more of hydrochloric acid. The two-step leaching method for leaching the zirconium component is an industrially advantageous method and is one of the features of the present invention.

Therefore, such a two-step leaching is necessary to remove most of the non-th@ materials from the zirconium oxychloride eluate.

In the method of the present invention, calcium chloride is then added to the zirconium leachate thus obtained to precipitate and separate zirconium oxychloride crystals.

According to the measurement results carried out by the present inventors, the relationship between the solubility of zirconium oxychloride and the concentration of calcium chloride is expressed by the curve shown in Figure 1. According to Figure 1, the saturation concentration of zirconium decreases as the concentration of calcium chloride increases. The solid phase is Zr0Cf in the solubility curve region shown in the figure.
Only fiz·8H20 exists in equilibrium. Furthermore, as the concentration of hydrochloric acid increases, the solubility of zirconium decreases even with the same concentration of calcium chloride.6 As mentioned above, it is possible to add calcium chloride to the zirconium leachate obtained by the method of the present invention and recover zirconium as zirconium oxychloride. For example, adding calcium chloride to the zirconium leachate as CaCb32
09/l, most of the zirconium precipitates as zirconium oxychloride crystals when the 1-(C1 concentration is 2 mol/l), and the dissolved zirconium becomes Z r
o 210 g//(23°C) or less, and zirconium can be efficiently recovered. Furthermore, the mother liquor from which the zirconium oxychloride crystals have been separated has a relatively low concentration of hydrochloric acid, which is advantageous in terms of waste liquid disposal.

EXAMPLES] Hereinafter, the present invention will be specifically explained with reference to Examples, but the method of the present invention is not limited thereto.

Example I Z r The molar ratio of O2 and CaO is 1=3.
After weighing the zircon sand and quicklime and mixing them uniformly,
Melted in an electric furnace. The heating melting temperature of the molten material at this time is 2
The temperature was 300° C., and then the melt was quenched with a water stream, dried and ground to obtain a molten product. As a result of analyzing this melted product, Zr0z34.8%, Ca047.7%,
It had a composition of 16-9% SiO2, and the particle size was 150 μm or less when sieved. In addition, in X-ray diffraction analysis, C
Only the aZrOs diffraction peak was identified.

Next, add 750 g of 7.51.35% water and hydrochloric acid to a 101 glass beaker, and while stirring, 45 g of the pulverized molten product.
0 g was added and heated and held at 25°C for 2 hours. Next, this slurry was separated from P, and the obtained leaching residue was diluted with water for 2 hours.
The mixture was washed out into a beaker, and 35% hydrochloric acid 4502 was added to bring the total volume to 11. The mixture was heated with stirring and kept at 90°C for 2 hours.

Next, this slurry was separated and the filter cake was washed to obtain a zirconium-containing leachate 11. Fe in the leachate
, AI! , T1, S;, etc., and as a result of quantitative analysis, Ai! in terms of oxide relative to Z r O2!
20*0.60%, F'ezO3o, 07%, S I
o20, 33%, and TiO20, 34%.

Next, 600% of a 40% CaCl2 solution was added to this leachate 11.
g was added to precipitate zirconium oxychloride crystals. Filter the crystals through a Buchner filter.

330 g of zirconium oxychloride was obtained. When this crystal was analyzed, the impurity content was S + 02 near 5
p'pm, Ti0z: 80ppm, AIto>: 8
5 ppm, Fe20t: 30 pl) Ill, and it was found to be highly pure zirconium oxychloride.

[Effects of the Invention] As explained above, the method for producing zirconium oxychloride of the present invention enables industrially and inexpensively producing high-purity zirconium oxychloride from zircon sand, which is a raw material containing impurities, through normal industrial operations. There are excellent effects that can be provided.

The highly purified zirconium oxychloride produced by the method of the present invention can be used for various purposes including as a raw material for producing zirconia, and is extremely advantageous.

[Brief explanation of drawings]

The figure is a graph showing the relationship between the solubility of zirconium oxychloride and the concentration of calcium chloride. Patent applicant Nihon Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. (a) A melt generation step of heating and melting a raw material mixture of zircon sand and a CaO-containing raw material and then rapidly cooling it to obtain an acid-soluble melted product; (b) the acid-soluble melted product. and a dilute aqueous hydrochloric acid solution to selectively elute and separate the calcium silicate component; (c) contact and dissolve the zirconium component with concentrated hydrochloric acid, separate the insoluble component, and recover the zirconium leachate; A zirconium oxychloride characterized by comprising a leaching step, and (d) a crystallization separation step of adding calcium chloride to the zirconium leachate to precipitate zirconium oxychloride crystals and separating and recovering the obtained crystals. manufacturing method. 2. The method for producing zirconium oxychloride according to claim 1, wherein the raw material mixture is a mixture in which the molar ratio CaO/ZrO_2 is in a range of 2.5 or more. 3. The acid-soluble melt product is amorphous or Ca
Claim 1 in which only ZrO_3 crystal phase is recognized.
The method for producing zirconium oxychloride as described. 4. The method for producing zirconium oxychloride according to claim 1 or 3, wherein the acid-soluble molten product is a powder with a particle size of 150 μm or less. 5. The method for producing zirconium oxychloride according to claim 1, wherein the step of concentrating the zirconium component is carried out at a HCl concentration of less than 2 mol/l in the slurry. 6. The method for producing zirconium oxychloride according to claim 1, wherein the zirconium leaching step is carried out at a HCl concentration of 2 mol/l or more in the slurry.