CS243379B1 - Process for preparing zirconium yellow pigment from zirconium mineral - Google Patents

Abstract

Method for preparing a yellow ceramic pigment of the zircon type containing praseodymium ions from the zircon mineral. The starting mineral is subjected to alkaline decomposition with potassium and sodium hydroxides at a temperature of 700 to 1,000 °C. The mixture of hydroxides is used only in the most necessary amount so that the decomposition takes place with sufficient efficiency and at the same time there is no need to wash out the alkali ions and the calcination. These ions are then used as the alkaline component of the mineralizer during the actual preparation of the product. The halogen component of the mineralizer is added in the form of an appropriate amount of hydrofluoric and hydrochloric acids. A chromophore is then added to the product, which is then in the solid phase, and a yellow zircon pigment is prepared by firing at 800 to 1,000 C. The invention can aí| used in the ceramic industry, as it allows the preparation of high-quality ceramic pigment and cheaper raw material extraction.

Description

(54) A process for preparing a yellow zirconium pigment from a zirconium mineral

A process for the preparation of a yellow ceramic pigment of the sircon type containing praseodymium ions with a sircon mineral.

The starting mineral is subjected to an alkaline decomposition of more potassium and sodium hydroxides at a temperature of 700 to 1000 ° C.

The mixture of hydroxides is used only in the minimum amount necessary for the base to be carried out with sufficient efficiency, without the need to wash the alkali ions and the stillage. These ions are then used as the alkaline component of the minaralizer in the actual preparation of the pieent. The halogen component of the aineralizer α adds the appropriate amount of hydrofluoric acid and hydrochloric acid in the forum.

A chromophore is further admixed to the solid phase product and fired at 800 to 1000 ° C to prepare a yellow sircon pigment.

Vynálea can aí | the use of κ ceramics industry, because it allows the preparation of high-quality ceramic pigpant and cheaper raw material feedstock.

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of a yellow ceramic pigment of the Slron type from a zirconia mineral.

Zircon pigments are most often prepared with the emission of starting mineral oxides of zirconium and silicon, which are fired together with mineralizers and chromophores. The second method is based on a cheaper zirconium mineral, which in the first step must first be decomposed into a zirconium and siliceous component.

It is only from the products of its decomposition, possibly after further processing, that the pigment is prepared in the second stage. Zircon is a thermally and chemically very stable substance. Existing decomposition processes are based on alkaline melting of mineral, chlorination in reducing environment at high temperatures, or direct decomposition by high temperatures or by plasma.

However, these methods also have disadvantages. Methods of direct decomposition by high temperature or plasma are very simple from the point of view of further processing of decomposition products into pigment, but from the energy point of view they are disproportionately demanding operations.

The same is true for the decomposition of zirconium in a reducing environment in connection with chlorination.

In addition, the need for processing the product into a suitable pigmentary zirconia does not require that the siliceous mineral component, although substantially cheaper than zirconia, is separated in a form not usable in the second stage for the preparation of the elongated pigment.

In the case of an alkaline decomposition of zirconium into a zirconium and siliceous component as part of the preparation of zircon pigments, soda is used practically exclusively. However, the processes require the use of disproportionately large amounts of soda with respect to the amount of decomposed mineral and relatively high temperatures to achieve a sufficient degree of zirconium decomposition.

In addition, they generally require further processing of the decomposition products into a mold useful for the preparation of zircon pigments. Mostly, the decomposition products are subjected to difficult water leaching, most often with the addition of sulfuric acid.

Again, the need to obtain the zirconium and siliceous components from the extracts complicates the pigment preparation process. In the case of the silica component, losses often occur, so that it is necessary to add silica to the pigment preparation.

There are also procedures to treat decomposition products after melting with soda, only by adding sulfuric acid, so that they remain practically in solid form, and when supplemented with mineralizers and chromophores, the pigment is fired directly from them.

However, its quality is low, both in terms of the degree of conversion to zirconium silicate and in terms of color. In addition, the pigment leachate has to be intensively leached to remove large amounts of sodium salts.

Said drawbacks do not have a process for the preparation of a yellow sintered pigment from a zirconium mineral, characterized in that the zirconium mineral is decomposed by melting with a mixture containing zirconium. potassium hydroxide and sodium hydroxide in wt. a ratio of 3 to 1: 1, preferably in wt. a ratio of 2 to 1.5: 1 in such a way that 10 wt. 3 to 6 wt. parts, preferably 4 to 4.5 wt. parts of this mixture.

Waste hardening baths from the mechanical engineering industry containing potassium and sodium hydroxide in a ratio of approximately 3 < 2 >

The decomposition melting itself is carried out at 700 to 1000 ° C, preferably at 800 to 900 ° C. Alkali were used for decomposition only in relatively small amounts, so they can be used without

I removed by leaching directly from the decomposition products to prepare a yellow zircon pigment.

Moreover, the decomposition took place to a high degree with the temperatures commonly used in ceramic pigment technology.

The decomposition products are aaea and potassium-potassium-silicate and zirconium-disodium silicate. After addition of the decomposition products by chromophores and halide ions as components of the aineralizer, the alkaline components of the aineralizer are potassium and sodium ions present in the silicates, a yellow zirconium pigment can be prepared by firing directly.

The cooled pelletized products are therefore sprinkled with hydrofluoric acid in amounts of 0.85 to 2.3, preferably 1.2 to 1.6 wt. % of hydrogen fluoride e 0.5 to 1.3, preferably 0.7 to 0.9 wt. 0.4 to 1.6, preferably 0.9 to 1.1 wt. and the mixture is baked at a temperature of 800 to 1000 ° C, preferably at a temperature of 880 to 920 ° C, to form a yellow zirconium pigment.

The residue content of the aineralizer is relatively low in the stillage so that the product can be directly used for application in a ceramic glaze, including glazes with a high glazing temperature of about 1300 ° C.

However, it may be eliminated with water or a dilute mineral acid to improve the pigment quality.

Advantages of the method according to the invention:

The decomposition temperatures are favorable and correspond to the temperatures commonly used in the ceramic industry

- the amount of alkaline flux required for decomposition is low and waste mechanical quenching baths containing potassium and sodium hydroxide can and successfully be used

- the degree of zirconium mineral degradation is greater than 95 ·

the process does not require a difficult leaching operation of the decomposition products

- in the actual preparation of the pigment, the alkali components of the mineralball are no longer added, since alkali ions are used in decomposition products

the pigment firing temperatures are favorable and correspond to the pigment firing temperatures of their preparation of zirconia and silica

- the pigment quality is in terms of degree of reactivity to zirconium silicate (occlo 85 *) and the color of the plgnent comparable to pigments prepared with a mixture of zirconium and silicon dioxide

the yield of the process according to the invention is high and makes it possible to prepare a pigment in an amount corresponding to more than 80% by weight of the starting zirconium

Examples of use of the invention are given below.

Example 1 g of zirconium mineral (containing 94% zirconium silicate) was decomposed with 30 g of a mixture of potassium hydroxide and sodium (KOH / NaOH weight ratio equal to 2) at 900 ° C for 2 h.

After cooling, the mixture was carefully poured over 25 g of hydrofluoric acid at 38 * concentration and 15 g of hydrochloric acid at 35 * concentration. 7.5 g of prmseodymium oxide (Pr 2 O 3) were admixed and the mixture was fired at 900 ° C for 2 h.

The leach was leached with dilute hydrochloric acid while hot. 58.9 g of a yellow zirconium pigment were obtained which contained 86.2% zirconium silicate. The pigment was applied in an amount of 5% by weight of a high temperature ceramic glaze with a glazing temperature of 1280 ° C, which it dyed to a yellow hue.

2 * 3379

Example 2

100 g of zirconium mineral (· containing · 96 * zirconium silicate) was decomposed by 42 g of spent mechanical quenching bath containing potassium and sodium hydroxide in haot. of 3 sec. 2 s and a temperature of 850 ° C for 2 h.

The cooled mixture was poured over 40 g of hydrofluoric acid at 38% concentration and 20 g of hydrochloric acid at 35% concentration, and then 9 g of praseodymium oxide (Pfg ⁰ ,,) was added. The mixture was fired at 850 ° C for 2 h.

After cooling, the slurry was washed with water and hot, and the remaining solid phase was 83 g of a yellow sircon pigment containing 82% sulfonium silicate. The pigment was applied in an evenness of 6% to a borosilicate glaze with a glazing temperature of 1050C, which it dyed to a yellow hue.

Claims (1)

P S SDŽI TXKÁLSZU A process for the preparation of a yellow sircon pigaent from a zirconium mineral characterized by the fact that the zirconium sulfide decomposes the melting of a mixture of hydroxides containing potassium hydroxide and sodium hydroxide x haot. 3 to 11 with 1, preferably in haot. ratio of 2 to 1.5: 1, tia xsobea, is per 10 haot. parts of zirconium will use 3 to 6 haot. parts, preferably 4 to 4.5 haot. and the decomposition is carried out at 700 to 1000 ° C, preferably at 850 to 950 ° C, after which the cooled decomposition products are sprinkled with hydrogen fluoride and hydrochloric acid in amounts of 0.85 to 2.3, preferably 1.2 to 1.2. 1,6 haot. % of hydrogen fluoride and 0.5 to 1.3, preferably 0.7 to 0.9 haot. 0.4 to 1.6, preferably 0.9 to 1.1 haot are added. a portion of praseodymium oxide or praseodymium salt of an oxidic acid and aaes is baked at a temperature of 800 to 1000 ° C, preferably at a temperature of 880 to 920 ° C, to a yellow zirconium pigment which may be removed by water or a dilute mineral acid .