RU2655336C1 - Method of obtaining iron oxide pigments - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention can be used in the preparation of pigments for the coloring of plastics, concrete, ceramic tiles, faience, porcelain products. To obtain iron oxide pigments, pyrite cucumber is subjected to rolling with concentrated sulfuric acid. Pellets are subjected to sulphating firing at temperature of 250–300 °C and then ultrasound-intensified aqueous leaching. From a mixture of water-soluble sulfates, obtained as a result of aqueous leaching, metal copper is isolated by cementation on iron. Then ammonium water is added and the hydroxides of titanium, aluminum, and zinc are sequentially separated. Filtration separates the precipitate of iron hydroxide Fe(OH)₂ and subjected to thermal oxidation in an air current at a predetermined temperature in the range of 400 to 1,000 °C depending on the chosen color of iron oxide pigments. Filtrate after the separation of iron hydroxide is oxidized with air oxygen, intensifying the process by ultrasound. Obtained precipitate of the yellow pigment FeO (OH) is isolated by ultrasonic filtration and dried at a temperature of not more than 120 °C. Filtrates are combined to form a liquid fertilizer, or evaporated to produce a fertilizer in the form of anhydrous ammonium sulfate.

EFFECT: invention makes it possible to obtain iron oxide pigments of a wide color range from pyrite cinder, as well as fertilizer.

1 cl, 2 ex

Description

The invention relates to the field of technology of inorganic substances and can be used to obtain iron oxide pigments of a wide color gamut for coloring plastics, concrete and products from them, ceramic tiles, earthenware, porcelain and some other technical fields.

The present invention is to develop a method for producing iron oxide pigment from a pyrite cinder.

The problem is solved by the fact that the pyrite cinder is subjected to pelletizing with concentrated sulfuric acid, after which the pellets are subjected to sulfatizing firing at a temperature of 250-300 ° C, and subsequently to ultrasonicated water leaching, and the subsequent precipitation of iron hydroxide, which is subjected to thermal oxidation in air flow at a given temperature in the range (400 ÷ 1000) ° C, depending on the selected color from the color gamut of iron oxide pigments, and the filtrate after separation of the hydroxide iron is oxidized with atmospheric oxygen, intensifying the process with ultrasound, and the resulting precipitate of yellow FeOOH pigment is isolated by ultrasonic filtration and dried at a temperature of ≤120 ° С, while the filtrates are combined to obtain liquid fertilizer or evaporated to obtain fertilizer in the form of anhydrous ammonium sulfate.

The process is implemented as follows: a pyrite cinder is subjected to pelletizing in order to obtain strong granules (pellets, pellets), and concentrated sulfuric acid is used as a binder to obtain pellets, after which the obtained pellets are subjected to sulfatizing roasting at a temperature of 250-300 ° C, and then - water leaching intensified by ultrasound, as a result of which iron compounds pass into the aqueous solution, forming iron sulfate, as well as sulfates of copper, zinc, aluminum and partially titanium.

From a mixture of water-soluble sulfates, metal copper is precipitated by iron cementation by the reaction:

Fe + CuSO ₄ → → Cu + FeSO ₄ ,

and then metal hydroxides are precipitated from sulfate-containing solutions by fractional precipitation by changing the pH of the medium by adding ammonia water (an aqueous solution of NH ₄ OH):

- at pH (1.5 ÷ 2.2), titanium hydroxide (TiO (OH) ₂ ) is completely precipitated;

- at pH (3.5 ÷ 5.5) precipitated Al (OH) _3;

- at pH from 5.4 to 7.5, Zn (OH) _{2 is} completely precipitated;

- at pH (8 ÷ 9.5) from an aqueous solution in which iron sulfate (iron sulfate) remains, the precipitate of iron hydroxide (P) formed during this process is isolated by the reaction

The precipitate Fe (OH) _{2 is} separated and subjected to thermal oxidation in a stream of air at a given temperature in the range (400 ÷ 1000) ° C, depending on the selected color from the color gamut of iron oxide pigments.

The filtrate obtained after separation of iron hydroxide is oxidized with atmospheric oxygen, intensifying the process with ultrasound, for 0.5-1.0 hours. The resulting yellow pigment FeOOH resulting from oxidation is isolated by ultrasonic filtration and dried at a temperature of ≤120 ° С.

The filtrates after the first and second stages of filtration are combined to obtain liquid fertilizer, or evaporated to obtain fertilizer in the form of dry ammonium sulfate.

Currently, of the widely known, fundamentally different methods for producing iron oxide pigments, the most common methods based on the Penniman process are:

2Fe + _^1/2 O ₂ + 3H ₂ O → formation yellow embryos

2FeO (OH) + 3H ₂

Fe + H ₂ SO ₄ - + FeSO ₄ + H ₂ ↑

(Penniman Jr. RS, Zoph NM Process of manufacturing iron compounds US 1327061 A, 1917), in accordance with which a solution of iron sulfate is prepared by dissolving iron-containing waste in sulfuric acid, after which the nuclei are prepared by oxidizing a suspension of freshly prepared iron (II) oxide hydrate in aqueous solution of iron sulfate and oxidized with atmospheric oxygen in a separate reactor. The embryos thus prepared are fed to the pigment synthesis reactor, where the pigment is synthesized at a temperature of (60 ÷ 70) ° C by oxidizing with air oxygen an aqueous solution of iron sulfate, and the oxidation time is (3 ÷ 4) days. The disadvantage of this method is the difficulty in implementation, multi-stage and the duration of the process.

A known method of sulfatizing roasting of a material containing non-ferrous metals (Markov A.D., Filatov Yu.V., Dorofeeva GG, and others. A method of sulfatizing roasting of a sulfide material A.S. 3415691, 1980) in order to produce production gas, not containing sulfuric anhydride and oxygen. The method is not aimed at obtaining iron oxide pigments.

Laboratory research is known (Martirosyan M.V., Grigoryan G.S., Grigoryan S.K. Application of sulfatizing roasting in the processes of complex extraction of valuable components of their polymetallic concentrate, Scientific notes of Yerevan State University. Chemistry, 2010, 2, p. 19- 23), the effectiveness of sulfatizing calcination, and it is shown that by means of sulfatizing low-temperature calcination of the concentrate followed by acid leaching of the calcined calcine, in principle, valuable non-ferrous metals can be extracted. The possibility of obtaining iron oxide compounds and pigments is not discussed in the work. The mentioned study also did not receive confirmation of the possibility of scaling.

Known methods for producing black pigment (Ismagilova G.V., Kolesnikova M.P., Kuznetsov A.I. et al. Method for producing black iron oxide pigment. RU 2346018, 2007, and Kalinichenko II, Sokolov V.I., Nikonenko E.A. et al., Method for producing iron oxide pigments. RU 2047631. 1995) from red mud by calcination at a temperature of (50 (H1000) ° C. The disadvantage of the above methods is the low quality of the pigment due to the low content of iron oxide and a large amount of impurities silicon and aluminum.

All methods for producing pigment by the Lauks process (Belenky EF, Riskin IV Chemistry and technology of pigments. Ld, “Chemistry”, 1974; Orlova OI, Fomicheva TN Technology of varnishes and paints. L-d, Chemistry, 1990) have significant drawbacks - the use of toxic nitrotoluene and the complexity of the process.

A known method for producing iron oxide pigments (Khabarov Yu.G., Babkin I.M., Kuzyakov N.Yu., Malkov A.V. Method for producing crystalline iron oxide (III). RU 2501737, 2007), including the introduction of iron salts into the solution (P) sodium nitrite, followed by the addition of alkali, separation of the precipitate obtained from the mother liquor, washing until neutral and drying. The disadvantage of this method is the complexity, the long duration of the process, a significant consumption of sodium nitrite and monostage, which greatly complicates the hardware design of the process.

A known method for producing red iron pigment nuclei, according to which a precipitate of iron hydroxide is prepared from a solution of iron (II) sulfate and ammonium sulfate by adding an aqueous solution of ammonia, the suspension is stirred for 30 minutes and then air is blown for two hours and then the suspension is boiled in two hours. (Leont'ev N.A. et al. A method for producing embryos of red iron oxide pigment. SU No. 1458368, 1989). The disadvantage of this method is the complexity and length of the process.

There is a method of complex processing of pyrite cinders (Romanenko G.M. and Yanovskaya T.A. Method of complex processing of pyrite cinders AC 644872 A1, 1979). This goal is achieved by the fact that the processing is carried out by electrolysis from a suspension of cinder in a sulfuric acid electrolyte on a magnetic cathode. The method is complex and is not aimed at obtaining iron oxide pigments.

A known method of producing iron oxides from metallic iron, including its interaction with an aqueous solution of a carboxylic acid in an inert gas medium, followed by oxidation to iron (III) carboxylate when heated in air. (Konka E. et al. Method for the production of iron oxides RU 2318730. 2003). The method is multi-stage, long and energy-intensive.

A patent is known (Mleczko L., Meisen U., Lamp G., Weber R. Iron oxide pigments US 7425234 B2. 2003), in accordance with the description of which, to obtain pigments of iron oxide, an aqueous solution of iron chloride is sprayed into a vacuum reactor, the drops are completely dehydrated to form solid particles, which are then heat treated in another reactor for up to 6 hours.

Judging by the description, the implementation of the method requires a long time and complex equipment and is aimed at obtaining only yellow-red pigment.

A patent is known (Takada J., Hashimoto N., Fujii T., Nakanishi M. Iron oxide red pigment. US. Appl. No. 20140134216. 2014) for a method for producing red pigment in the form of a hematite composite. Obtained by the specified method, the red pigment contains, in addition to microcrystalline iron, significant amounts of foreign matter in the form of silicon and phosphorus compounds.

A patent is known (Yang Jianming, Tan Gang, Shao Yuxiyng. Preparation technology for low water-absorption heavy iron oxide yellow pigment. CN 102390871 A, 2012) for a method for producing yellow iron oxide pigment. The process of obtaining pigment is associated with a high consumption of alkali, and the final product contains an admixture of zinc as an extraneous inclusion.

It should be noted that all of the above methods include a filtering process, which is the most time-consuming stage of the process chain. However, the filtration rate can be significantly increased by intensifying it with ultrasound. (Golyamina I.P. Ultrasound. Small Encyclopedia. Publishing House: Soviet Encyclopedia, 1979, p. 348; Akopyan VB, Yershov Yu.A. Fundamentals of the Interaction of Ultrasound with Biological Objects. Moscow, URAIT Publishing House , 2016, 223 S.).

A device for filtering in an ultrasonic field through a membrane element (Weavers L.K., Walker H.W., Lamminen M.O., Dong Chen. Ultrasonically cleaned membrane filtration system, US 7008540 B1, 2003). However, the principle of the device requires the density of ultrasonic energy, providing ultrasonic cavitation, in which not only the surface of the filter membrane is cleaned, but the filter element itself is destroyed.

A device for filtering in an ultrasonic field (Kovalev A.A., Ultrasonic filter, RF Patent 2037327, 1995), intended for water purification. The design of the filter is very complex and cannot be adapted to effectively filter suspensions.

A device for filtering in an ultrasonic field (Ivanova MA, Ponedelchenko AA, Development of an experimental ultrasonic installation with ceramic membrane elements for wine processing. Scientific journal NRU ITMO. Series "Processes and Food Production Equipment", 2015. No. 1 C . 56), designed to study the process of destabilization of the colloidal system of wine in a laboratory setting by ultrasonic treatment. The installation has low productivity and cannot be used without major alterations on an industrial scale.

In an idealized case, the filtering rate:

where V is the volume of the filtrate, S is the area of the filtering baffle, t is time, ΔР is the pressure difference on both sides of the filtering baffle, η is the viscosity of the liquid phase, R _OS is the hydrodynamic resistance of the sediment layer, R _fp is the hydrodynamic resistance of the filtering baffle.

The efficiency of transport processes is significantly increased under the influence of ultrasound, accelerating transport through porous materials.

As a result of ultrasonic action, the hydrodynamic resistance of the sediment remains equal to zero during the entire filtering process, and the resistance of the filtering wall decreases due to the reduction of diffusion restrictions at its surface. It is obvious that the material of the filtering septum, together with the liquid contained in it, absorbs part of the ultrasonic energy, which leads to an increase in temperature, a decrease in the viscosity of the liquid in the pores of the septum, and, consequently, to an increase in the filtration rate.

The use of ultrasound in the pre-cavitation mode allows you to intensify the filtering process due to acoustic flows, but to maintain the integrity of the filter element and suspended particles.

The invention is demonstrated by examples, which are not, however, restrictive.

Example 1

The pyrite cinder is dipped on a granulator with the gradual addition of sulfuric acid with a concentration of 85-92%. The obtained pellets are dried for hardening and fired at a temperature of 250-300 ° C, then sent to the operation of water leaching at a temperature of 80-90 ° C for 0.5-2.0 hours. In the process of water leaching, water-soluble sulfates of iron, copper, zinc, aluminum and partially titanium are transferred to the solution, which are separated from the insoluble residue by filtration. From the resulting aqueous solution, metal copper is isolated by carburizing on iron, and subsequently, titanium, aluminum, and zinc hydroxides are precipitated by fractional precipitation. After such a sequence of operations, iron sulfate (iron sulfate) remains in solution. From a solution of ferrous sulfate (vitriol) at pH 8.7 ± 0.7 created by adding an ammonia solution, the precipitate of ferrous iron hydroxide Fe (OH) _{2 is} separated by filtration, the precipitate is washed with water and sent to the thermal oxidation operation at a given temperature to get the pigment in the right color. The filtrate of the first stage of precipitation of iron hydroxide is oxidized with atmospheric oxygen at a pH of 8.7 ± 0.7 for 0.5-2.0 hours to obtain a yellow pigment, which is isolated by filtration and dried, the cake obtained at a temperature of ≤120 ° С.

The liquid phase after the first and second filtration is combined and used as a liquid fertilizer, or evaporated to obtain dehydrated ammonium sulfate.

The process is characterized by the following indicators: pigment yield at the first stage of deposition (75 ÷ 80)% and at the second - (25 ÷ 20)%, while pigments are obtained with the content of iron oxide (97.8 ÷ 99.9)% and with bright color characteristics.

Example 2

differing from example 1 in that the iron hydroxide (P) obtained in the first stage of ammonia deposition is subjected to thermal oxidation at various temperature conditions, providing the pigment of the desired color.

- to obtain a red-brown pigment, thermal oxidation is carried out at a temperature of 400 ÷ 500 ° C, while the content of iron oxide in the obtained pigment is 98.72%, sulfur 0.68%, phosphorus pentoxide <0.03%.

- the red pigment is obtained by thermal oxidation at (550 ÷ 650) ° C, a pigment with a content of iron oxide of 98.95%, sulfur 0.51% is obtained. Phosphorus pentoxide less than 0.03%.

- red-lilac pigment is obtained by thermal oxidation at 650 ÷ 700 ° C, to obtain a pigment containing with a content of 98.8%, iron oxide and sulfur content of 0.41%, and phosphorus pentoxide less than 0.035.

A pigment containing iron oxide with sulfur content was obtained.

- lilac pigment is obtained by thermal oxidation at (700 ÷ 750) ° C, to obtain a pigment containing 98.38% iron oxide and a sulfur content of 0.53%.

- lilac-black pigment is obtained by thermal oxidation at a temperature of (750 ÷ 1000) ° С, 99.91%) of iron, and 0, .11% sulfur content.

Our additional studies on varying various physical parameters of the sulfatizing firing process, ultrasonic filtering and leaching, as well as searching for optimal modes for producing iron oxide pigments, showed that when each of these parameters changes, both increase and decrease (with the remaining parameters being constant ), the efficiency of the processes decreased. Studies have shown that the parameters of the claimed method, as described in the claims, are optimal, and the invention can be carried out using the means and methods described in the application.

Thus, the above information indicates that the presented invention has the claimed properties, and the combination of distinctive features of the described method ensures the achievement of the specified result.

As a result of the analysis of the state of the art of sulfatizing firing, ultrasonic filtering and leaching, as well as the production of iron oxide pigments, an analogue characterized by features identical to all the essential features of the claimed invention was not found, therefore, the claimed invention meets the condition of "novelty."

An additional search for known solutions showed that the claimed invention does not follow explicitly from the prior art for a specialist, since new conditions for intensifying processing processes are selected, as well as the totality and sequence of technological methods providing low-waste, accelerated production of iron oxide pigments of a wide gamut of colors, as well as fertilizers as a by-product. Therefore, the claimed invention meets the condition of "inventive step".

For the claimed method, in the form as described in the claims, there are no obstacles to its implementation in practice using modern technical means. Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (1)

A method of producing iron oxide pigments from a pyrite cinder, characterized in that the pyrite cinder is subjected to pelletizing with concentrated sulfuric acid, after which the pellets are subjected to sulphatizing firing at a temperature of 250-300 ° C and subsequently ultrasonically intensified aqueous leaching, then from a mixture of water-soluble sulfates, as a result of water leaching, metallic copper is first isolated by carburizing on iron, after which ammonia water is added and hydroxy is sequentially isolated titanium, aluminum, zinc, then, by filtration, a precipitate of iron hydroxide Fe (OH) _{2 is} isolated, which is subjected to thermal oxidation in a stream of air at a given temperature in the range from 400 to 1000 ° C, depending on the chosen color from the color gamut of iron oxide pigments, and the filtrate after separation of the iron hydroxide, they are oxidized with atmospheric oxygen, intensifying the process with ultrasound, and the resulting precipitate of yellow FeO (OH) pigment is isolated by ultrasonic filtration and dried at a temperature not exceeding 120 ° C, while the filtrates are combined to obtain a liquid fertilizer, or evaporated to obtain fertilizer in the form of anhydrous ammonium sulfate.