CS273049B1 - High-temperature method of double zinc-nickel cyclo-tetraphosphates preparation - Google Patents

Abstract

The invention is based on the calcination of the initial mixture composed of compounds of the zincous and nickelous types of dihydrogen-phosphates, or mixtures of phosphoric with zincous and nickelous phosphates or hydrogen-phosphates, or with zinc and nickel oxide, hydroxide, carbonate or hydrogen-carbonate in quantities corresponding to the molar ratio Zn/Ni = (2-x)/x and P2O5/(Zn+Ni) equal to 0.99 to l.06 to temperatures higher than 810 degrees C, when melting occurs. By intensive cooling this is transformed into a vitreous intermediate product, which, by repeated heating to a temperature of at least 580 degrees C and lower than 810 degrees C, re-crystallises, causing the occurrence of micro-crystals of zinc-nickel double cyclo-tetraphosphates.

Description

(57) The solution consists in calcining the starting mixture, composed of zinc and nickel compounds of the dihydrogen phosphate, resp. mixtures of phosphoric acid with zinc and nickel hydrogen phosphates or phosphates or with zinc and nickel oxides, hydroxides, hydroxides, carbonates or carbonates in amounts corresponding to moles. a ratio of Zn / Nl (2-x) / x and Ρ2θ§ / (Ζη + Ni) equal to 0.99 to 1.06, to temperatures above 810 ° C, resulting in a melt which is quenched to a glassy intermediate was repeated by heating to a temperature of at least 580% ^D C and lower than 810 ° C, recrystallizes to form the microcrystals of the double-cyclo tetrafoeforečnanů zinc nikslnatých.

273 049 (1), (13) Bl (51) Int. Cl. ⁵

OJ C 01 B 25/44

CS 273 049 Bl

The invention relates to a high-temperature process for the preparation of zinc-nicotinic double cyclo-tetraphosphates.

Zinc-nickel double cyclo-tetraphosphates ο-2η ₂ _ _χ Νί _χ Ρ ₄₀ ^ ₂ , ^x (j 2), are compounds of the cyclic anion-type condensed phosphate type consisting of four interconnected tetrahedra (PO ₄ ). Yellow-green compounds with high thermal and chemical stability with a crystal structure in a monoclinic system are applied. The present inventors disclose these compounds as novel compounds and propose a method for their synthesis which is based on the thermal treatment of a mixture of zinc and nickel oxide, hydroxide, carbonate or hydroxide-carbonate and phosphoric acid, using only temperatures where there is no melting of the products, ie up to 810 ° C. The process is advantageous from an energy and technological point of view, but sometimes it is necessary to prepare products with regular particles formed by well-developed microcrystalline ο-Ζη _{2 χ} Νί _χ Ρ ₄ Ο ^ ₂ , which are more preferred for some applications.

Preparation of Product E aforementioned particle properties and high purity according to the invention allows high temperature process for preparing double-cyclo tetrafoeforečnanů zinc-nickel, formula ^c_2n 2-x ^Ni x ^P 4 ⁰ * L2 ^{* 2)} · characterized characterized in that the starting mixture, composed of both dihydrogen phosphates, hydrogen phosphates, phosphates or oxides, hydroxides, carbonates or hydroxide-carbonates of zinc and nickel in such quantities that the molar ratio Zn / Ni corresponds to (2-x) / x, phosphoric acid in an amount such that the phosphoric anions in the mixture in a molar ratio of P20g / (Zn + Ni) equal to 0.99 to 1.05, preferably 1 to 1, QO5, are heated to the divalent cations, preferably wherein the heating rate is less than 30 ° C / min and the water vapor pressure in the calcination space is 40 to 100 kPa, to a temperature greater than 810 ° C, preferably greater than 1250 ° C, when the previously formed intermediates melt, whereupon the melt quenched, preferably by pouring into water or a cold plate of inert material, to form a further intermediate in the form of a homogeneous amorphous mass of glassy character, which is further, preferably after grinding, reheats to at least 580 ° C and below 810 ° C, β preferably to above 650 ° C and below 750 ° C, when recrystallization of the intermediate together with the rearrangement of the tetrahedra (P0 ₄ ) in the anion occurs to form double cycles Zinc-nickel tetraphosphates, which are preferably ultimately pulverized into finely divided particles of microcrystalline nature.

In the high-temperature process for the preparation of zinc-nickel (II) -cyclotaphosphates, it is possible to start from raw materials in which the phosphorus anions content of the respective divalent cations is expressed. a ratio of PgOg / fZn + Ni) of one or ss is close to one of - 0.99 to 1.06, preferably 1 to 1.005. Therefore, the axis can be started from a mixture of hydrogen phosphates or phosphates, so-called tertiary, (again in hydrate or anhydride form) and phosphoric acid. Starting materials of type phosphates are, however, wider technological use less desirable afraid require preparation in advance, which itself nsni simple operation, so that is more suitable only for preparing small quantities of products ^{ε_2η 2_χ Νί} · ^χ Ρ 4 ^{Ο ΐ2 in 2c} ® -1 - ^{and in} pure form. For technological applications, such as the synthesis of double cyclotetraphosphates for pigmentary or agrochemical purposes, it is preferable to start from a mixture of oxides or hydroxides, or zinc-nickel hydroxide-carbonates or carbonates with phosphoric acid. The acid can be used at any concentration, however, it should be appreciated that dilute acid is preferable for effective proragulation of the starting mixture, while higher concentration acid is more suitable for the energy requirement of evaporating water from the acid. The acid concentration must therefore be selected individually according to the reactivity of the starting compound and the energy potential of the potential manufacturer. When using a high concentration acid, at high heating rates there may be a risk of a separate condensation of phosphoric acid to higher polyphosphoric acids and at high temperatures even to phosphorus pentoxide which can volatilize from the mixture; thus adversely affecting the ratio of phosphate anions to divalent cations in the calcinate, reap. meltingCS 273 049 Bl. The first condensed phosphate-type intermediate formed during calcination; is a double dihydrogen diphosphate at temperatures of about 200 ° C. At temperatures of about 100 DEG to 200 DEG C., the latter is converted to the product; which to a greater or lesser extent corresponds to the double cyclotetraphosphates. In order to maximize the proportion of double cyclo-tetrafluorophosphates, which are also an intermediate in this phase, and to minimize the risk of separate condensation of the phosphorous component and, consequently, its volatilization loss, it is advantageous to conduct a heating rate of less than 30 °. C / min. in the presence of 40 to 100 kPa water vapor. Maintaining a water vapor pressure in the calcinate space of at least 40 kPa is advantageous to prevent the formation of undesirable by-products, in particular to prevent cleavage and separate condensation of the phosphorus component. The water vapor present in the individual condensation reaction somewhat slows down the formation of the intermediates, allowing them to be more quantitatively progressive. The final calcination temperature at this stage of the preparation of the product according to the invention is higher than 810 ° C; since this is already the temperature at which some of the intermediates start to melt due to the requirement for rapid melting of the calcinate, which may also contain other levels of the secreting agent, it is preferable to choose a temperature higher, i.e. above 1,250 ° C. The intermediate melts non-congruently, with the disintegration of the tetrafosphate cycles and the coupling of the resulting short phosphate chains into long chains, to which the presence of at least trace amounts of water vapor from the melt space contributes. Thereafter, the melt needs to be tuned sharply, preferably by pouring it into water or onto a cold plate of inert material (metal or ceramic). This will give another intermediate; which is a homogeneous amorphous mass of vitreous nature, containing long-chain anions. The piece of glass thus obtained is forced and cooled after cooling. drying is preferably ground to dryness and again heated so as to recrystallize the intermediate under rearrangements tetrahedra (P0 ₄₎ anion to give microcrystals of double cyclo tstrafosforečnanů zinc-nickel, formula ο-Ζη ₂ _ _{χ Ν1 χ Ρ 4} 0 ^ ₂ (x €? (0} 2)). This releases small amounts of chemically bound water in the glassy intermediate. Therefore, it is easier to conduct the process of thermal recrystallization if the glassy intermediate is dry-ground beforehand. The lower temperature of this reheat is 580 ° C and corresponds to the lower recrystallization temperature of the zinc-nickel intermediates. While this temperature can only be achieved, since the recrystallization process is exothermic and once it starts, it continues to run spontaneously, but the preferred temperature range for recrystallization is higher than 650 ° C and lower than 750 ° C, where the recrystallization of the glassy intermediate occurs heating rate and any consistency of the intermediate (powder, kue or completely compact) and there is no risk of melting the final product, which, due to its non-congruity, would again lead to the formation of a glassy intermediate. Thus, it is not possible to exceed the limit of 810 ° C during recrystallization, which corresponds to the lower melting point of the double products. The final products - zinc-nickel double cyclo-tetraphosphates - after cooling, are preferably further comminuted (grinding, comminution) to regular fine-grained particles of microcrystalline nature. If the glass product was ground prior to recrystallization, the final comminution of the products is very easy.

The process according to the invention further comprises treating the product after calcination with hydrochloric, sulfuric, nitric or phosphoric acid, preferably a concentration of 0.5 to 10% by weight. cleaning of obtained products in their pure form, eg for analytical or preparative purposes. The action of said acids removes all unwanted by-products and eventually by-products. residues starting! mixtures, which thus go into solution. The zinc-nickel double cyclo-tetraphosphates resist the action of these acids.

Advantages of the process according to the invention are the high yield and high purity of the products which can be further purified by leaching. Another advantage is the microcrystalline fine-grained character of the product particles, which are regular and very well developed on the surface.

Axes are therefore suitable for some special applications.

CS 273 049 Bl

Examples of the use of the process according to the invention are given below.

Example 1

Mixture of 100 g of zinc hydrogen phosphate (49,5% P ₂ 0 _g , ³³ » ⁸ % 2 °) ^and θ ⁶ »! 9 hydroganfoeforečnanu nickel (60.4% P20g; ³⁰ »5%) together with 157 g of phosphoric acid concentrations of 65 wt ·% HgP0 ₄ was calcined at 20 ° C / inin, wherein the tension of water vapor in the calcination chamber is maintained up to a temperature 500 ° C higher than 85 kPa, at a temperature of 1 260 ° C. The resulting melt was quenched by pouring into water. The glassy intermediate obtained was separated, dried and dry ground. It was then heated to 700 ° C and, after cooling, triturated. The product contained 96.2% zinc-nickel zinc-cyclophosphate double c-ZnNiP ₄₀ O ₂ and 235 g; it was in the form of regular fine microcrystals.

Example 2

A mixture of 100 g of zinc carbonate (47% Zn) and 25.6 g of nickel carbonate (53%

Ni) together with 380 g of phosphoric acid. concentration of 50% H ₃ P0 ₄ was calcined at 10 ° C / min while being TENZO water vapor in the calcination chamber is maintained at temperatures up to 550 C, ^D is higher than 80 kPa at a temperature of 1100 ° C. The resulting melt was quenched by pouring onto a corundum plate. The cooled glassy intermediate was dry ground, then heated to 680 ° C and triturated after cooling. It .získáno 222 g of product which contained 95.3% of double -cyclopentane-tetrapolyphosphate zinc-nickel formula C-Z ^ _{Q g} Ni 5 ^P 4 ° ¹² grained microcrystalline form.

Example 3

A mixture of 50 g of a zinc hydroxide slurry (containing 35% Zn) and 77.2 g of nickel hydroxide carbonate (containing 59% Ni) together with 250 g of 85% by weight phosphoric acid. The HgPO4 was calcined at a rate of 5 ° C / min, while the water vapor tan in the calcined space was maintained up to a temperature of 600 ° C above 75 kPa, to a temperature of 1250 ° C. The resulting melt was quenched by pouring into water. The glassy intermediate obtained was separated, dried and dry ground. It was then heated to 740 ° C. 236 g of product were obtained, which contained 97.3% of zinc-nickel zinc-orthophosphate double-cyclo-phosphate of the formula c-θηθ, 5 ^P 4 ^O 12 in microcrystalline form.

Claims (2)

OBJECT OF THE INVENTION 1. A process for preparing high-cyclo podvojnýchc tetrapolyphosphate zinc-nickel formula ^{c "Zn} 2-x ^Ni x ^P 4 ° i2 ^{'x e} i ^{c; (2} ) ^: characterized in that the starting mixture, composed of either dihydrogen phosphates, hydrogen phosphates, phosphates or oxides, hydroxides, zinc and nickel hydroxides, carbonates or carbonates, in such quantities that the molar ratio Zn / Ni corresponds to the formula (2-) x) / x, on the one hand from phosphoric acid in such an amount that the phosphorus anions are present in moles relative to the divalent cations. a ratio of P20g / (Zn + Ni) equal to 0.99 to 1.06, preferably 1 to 1.005, is heated, preferably such that the heating rate is less than 30 ° C / min and the water vapor in the calcite space is 40 to 100 KPa, to a temperature greater than 810 ° C, preferably greater than 1250 ° C when the previously formed intermediates melt, then the melt is quenched, preferably by pouring into water or a cold plate of inert material, to form a further intermediate as a homogeneous amorphous matrix glass which is furthermore preferably after milling again heated to a temperature of at least 580 and less than 810 ° C, preferably to a temperature higher than 650 and lower than 750 ° ^C which occurs recrystallization intermediate together with rearrangement of the tetraaders (PO 4) in the anion to CS 273 049 B1 4 the formation of double zinc-nickel cyclo-tetrafosphates, which is preferably comminuted to form fine-grained particles of microcrystalline character · 2. Process according to claim 1, characterized in that the kaleinael product is treated with hydrochloric, sulfuric, nitric or phosphoric acid, preferably a concentration of 0.5 to 10% by weight.