FI63205C - FOERFARANDE FOER ATT TILLVARATAGA DE FASTA PARTIKLARNA AMMONIUMDEKAVANADAT UR VATTENLOESNINGAR AV VANADATER - Google Patents

Description

ζϋάτ * 1 ΓΒΐ nivAdvertisement PUBLICATION, 70nc jjgflA lBJ 11 UTLAGGNINGSSKRIFT 6 3205 (45) C PatentI3oycnrie L ty 10 05 1983 * (51) Wfcft * q> 5d & iQ1 g 51/00 FINLAND — FINLAND (11) Paunttl - Patuttl H «fcM» l »pUvt — AmMwhHn l6.09 · 77 '* (73) Alkupllvl - GIMghMadag l6.09.77 (41) Translator Julkhuk ·! - Mvk offantllg l8.03.78

Patent j * r> k., Frlh »llltu, (44) Nlhttvilulpanon J · moonLlulkaiwn date. -

Patent- och ragitterttyralaan '' AmMcm utbgd ock utUkrtftwi cleantcwte 31.01.83 (32) (33) (31) used «uolk * u * —tegird prtorttat 17.09.76 Avenue, New York, NY 10017, USA (72) John Little Powell, Hot Springs, Arkansas, Peter Crouse Rekemeyer,

Grand Junction, Colorado, Earl Edward Falk, Grand Island, New York, USA (US) (7M Oy Borenius & C: o Ab (5 * 0 Method for recovering solid particles of ammonium decavanadate from aqueous solutions of vanadates - Förfarande för att tillvara-taga de fasta particulate ammonium decanadate in the water supply

The invention relates to a process for recovering solid particles of ammonium vanadate, consisting essentially of ammonium decavanadate dissolved in water.

It is common practice in the industry to treat vanadium ore to obtain aqueous solutions of vanadates, from which the valuable components of vanadium are recovered as a solid vanadate product useful in industry. The prior art method for recovering solid vanadate products is based on crystallization methods which result in contaminated wastewater due to the relatively low recovery of solids. Suspected of ammonium vanadate, the wastewater is contaminated with ammonia.

It is an object of the invention to provide a method for recovering valuable components of vanadium from aqueous solutions of vanadates so that vanadium is thoroughly recovered and the formation of contaminated wastewater is avoided.

Other objects of the invention will become apparent from the following description and claims, as well as from the drawing, in which only Figure 1 schematically shows a processing system for applying the invention.

2 63205

The process of the invention for recovering a solid vanadate compound from an aqueous solution is based on spraying an aqueous vanadate solution to form small droplets of this vanadate solution, passing these small solution droplets to a heated zone having a temperature in the range of about 300-750 ° C, preferably 400-550 ° C. , to evaporate the aqueous components of the droplets, and to form small solid vanadate particles, which small particles are rapidly cooled to a temperature of less than about 250 ° C, suitably less than about 150 ° G.

The invention will now be described in more detail with reference to the accompanying drawing, which illustrates how an aqueous solution of a vanadate compound is fed to line 10. The solution flows from nozzle 20 and thus nebulizes to form small droplets of vanadate solution into a fine mist.

Small droplets of the solution are exposed to a high temperature in the zone 30 of the chamber 40 in the range of 300 to 650 ° C. This temperature is provided by hot gases flowing into the chamber 40 from the inlet line 50. The small droplets of solution evaporate rapidly in zone 30, i.e. their water component evaporates, and very small particles of solid vanadate material pass through the line 50 as they enter zone 60. The temperature of the zone 60 is lower than about 250 ° C, which can be achieved by coordinating the structure of the chamber 40 and the cooling of the gases in the chamber 40 due to the evaporation of the liquid droplets. Alternatively, the lower part of the chamber 40 may be water-cooled in a manner known per se. By rapidly transferring the vanadate particles to the colder zone 60, the decomposition of these small vanadate particles, in the range of 0.5 to 100 μm, is avoided.

The small vanadate particles thus formed travel as a powder from the chamber 40, entrained by the gases fed from the inlet line 50, to a conventional cyclone system 70, from which the vanadate product is recovered by means of a collector device 80. The very small dusty particles are collected in a previously known filtration unit 90, and the exhaust gases and steam are transferred to the scrubber 110 by means of a fan 100 in a known manner.

The following example further illustrates the invention.

Example 3 63205

An aqueous solution of ammonium decavanadate (NH 4) gVxo ° 28 was fed in 2-liter portions through a centrifugal spray nozzle at different speeds into a vertical spray-drying chamber of the type shown in the drawing (steel jacket, thickness 1.6 mm, diameter of cylindrical cross-section diameter 76 cm, diameter 76 cm). The drying chamber was heated by the combustion gases of the natural gas-oxygen mixture which flowed through the chamber from its upper end to its bottom, as shown in the drawing. The gas temperature was measured at the inlet and outlet ends of the chamber. The vanadium content of the vanadate solution, measured as V 2 O 5, was 7.91% by weight. The results of the various experiments are shown in the following table:

Table I Ammonium decannadate solution Heating chamber

Flow- Heating gas inlet output vanadate volume space flow heat- heat recovery (ml / min) _ ° C volume (1 / min) space_status_ 154 45 40 368 127 83 «333 47 45 480 128 91« 400_42_51_538_128_88 « No NH3 was detected in the gas leaving the chamber.

Various prior art spraying devices can be used in the practice of the invention to form liquid droplets of a mist-like jet having a size of about 2 to 500 and m, as described in the Chemical Engineer Handbook, 3rd Edition, McGraw-Hill, pages 839 ... 840. Vanadium solutions other than ammonium decavanadate solutions may also be treated, e.g. ammonium metavanadate sodium decavanadate sodium metavanadate potassium decavanadate potassium metavanadate.

The recovered vanadate product can be decomposed by heat in a known manner to give an industrially useful product V20s.

Heating and gas flow systems known in the art other than those shown in the drawing may be used.

Claims (2)

4 63205 for the application of the invention, e.g. external heating and horizontal drying chambers as well as countercurrent gas flow methods. A process for recovering solid particles of ammonium decavanadate from a solution consisting essentially of ammonium decavanadate dissolved in water, characterized in that: 1. an ammonium decavanadate solution is sprayed through wherein the vessel has a heated zone having a temperature in the range of about 300 to 750 ° C to vaporize the water component of these droplets and to form small ammonium decavanadate particles, about 0.5 to 100 microns in size, and water vapor exiting the heated zone in said gas stream, 3. passing this gas stream and the small ammonium decavanadate particles and water vapor thus formed, leaving the heated zone, to an adjacent cooling zone below 250 ° C in said vessel and through it to the ammonium decavanadate flue; to prevent the decomposition of the particles, and 4. recovering solid, small ammonium decavanadate particles as they leave the cooling zone. A method according to claim 1, characterized in that the temperature of the heated zone is about 400 to 550 ° C, and the small ammonium decavanadate particles are cooled to a temperature below about 150 ° C.