RECOVERY OF VANADATE COMPOUNDS FROM AQUEOUS SOLUTIONS

RECUPERATION DE COMPOSES DE VANADATE CONTENUS DANS DES SOLUTIONS AQUEUSES

English Abstract

11036
RECOVERY OF VANADATE COMPOUNDS
FROM AQUEOUS SOLUTIONS
ABSTRACT OF THE INVENTION
Vanadium values are recovered from an aqueous
vanadate solution by atomizing the solution and heating
the fine droplets to vaporize the water constituent and
form vanadate particles which are quickly cooled.
S P E C I F I C A T I O N
-1-

Claims

WHAT IS CLAIMED IS:
1. Process for recovering a solid vanadate compound
from an aqueous solution thereof which comprises
(i) atomizing an aqueous vanadate solution to
provide fine droplets of vanadate solution
(ii) introducing said fine droplets of solution
into a heated zone which is at a temperature
in the range of about 300°C to 750°C to
vaporize the aqueous constituent of said
droplets and provide fine sized vanadate
particles and
(iii) rapidly cooling the thus provided fine sized
vanadate particles to a temperature below
about 250°C
2. Process in accordance with Claim 1 wherein the
temperature in the heated zone is from about
400 to 550°C. and the fine sized vanadate
particles are cooled to below about 150°C.
-7-

Description

The present invention is directed to the recovery
of vanadium values from aqueous vanadate solutions.
I~ is a common industrial prac~ice to process
vanadiurn ores to obtain aqueous vanadate solutions From
which the vanadium values are recovered in the form of
an industrially usable solid vanadate product. The
conventional prior practice for recovering solid vanadate
product involves crystallization techniques which result
in a contaminated liquid effluent due to relatively low
solids recovery. In the case of ammonium vanadate the
effluent is contaminated with ammonia.
It is an object oF the present invention to
provide a process for recovering vanadium values from
aqueous vanadate solutions which provide high recoveries
of vanadium and avoids the formation of a contaminated
liquid effluent.
Other objects will be apparent from the
following description and claims taken in conjunction
with the drawing wherein Figure I shows schematically a
process arrangement for the practice of the present
invention.
-2-

~L~9~; 2at;i7
A method in accordance with the present invention
for recovering a solid vanadate compound from an aqueous
solution comprises atomizing an aqueous vanadate solution
to`provide fine droplets of vanadate solution, introducing
the fine droplets of solution into a heated zone which is
at a temperature in the range of about 300 to 750C~
preferably 400 to 550C to vaporize the aqu ous constituent
of the droplets and provide fine sized solid vanadate
particles, and rapidly cooling the fine sized particles
to a temperature below about 250C, preferably below about
150C.
The present invention will be more fully under-
stood with reFerence to the drawing which shows an aqueous
solution oF vanadate compound introduced to conduit 10.
The solution passes through a nozzle 20 and is thereby
atomized into a fine spray of fine droplets of vanadate
solution.
The fine droplets of solution are subjected tu
a high temperature in zone 30 of chamber 40, i.e. in the
range of 300 to 650C. This temperature is established
by hot gases entering chamber 40 at inlet conduit 50.
The solution droplets are rapidly vaporized in zone 30,
i.e. the waterconSt;tuent is vaporized, and very small
particles of solid vanadate material is swept into zone 60
by the gases from conduit 50. Zone 60 is at a temperature
of less than about 250C which can be established by
coordinating the design of chamber 40 with the cooling of
the gases within chamber 40 due to vaporization oF the

liquid droplets. Alternatively, the lower portion of
chamber 40 can be conventionally water-cooled. By
rapidly moving the vanadate particles into cooler zone
60, decomposition of the small vanadate particles which
are on the order of 0.5 to 100 microns is avoided.
The thus produced dry, fine vanadate particles
in the form of a powder are swept from chamber 40 by
the gases from inlet 50 to a conventional cyclone
arrangement 70 from which vanadate product is recovered
at collector 80. Very fine dust-like particles are re-
covered at conventional filter unit 90 and the exhaust
gas and vapor are conventionally transFerred via blower
lO0 to scrubber llO.
The following example will further illustrate
the present invention.
EXAMPLE
A water solution of ammonium decavanadate,(NH4)6
V1028~ in the amount, in 2 liter amounts, was fed through
a centriFugal wheel atomizing nozzle at different rates,
into a vertica1 spray drying chamber of the type shown in
the drawing (steel shell .064in.thick, 30 in. cylindrical
section 30 in. diameter, 24 in. conical end section).
The drying chamber was heated by combustion gases from a
natural gas-oxygen mixture which passed through the chamber
from top to bottom as shown in the drawing. The gas temper-
ature was measured at the inlet and outlet of the chamber.
The vanadium content of ~he vanadate solution, measured as

25~
~25 was 7.91% by weight. The results of various tests
are shown in the following table.
TABLE I
Ammonium Deca-
vanadate Soln. Heating Chamber Chamber Ammonium Deca-
Flow Rate. Gas Inlet Outlet vanadate
Flow(CFM) Temp.
~S4 45 1.4 368 127 83%
333 47 1.6 480 128 91%
4~0 42 1.8 538 128 88%
H3 was not de~ec~ed in the gas exiting the chamber.In the practice of the present invention various
conventional atomizer devices which provide a mist-like
spray of liquid drops about 2-500 microns can be employed
such as described at pp 839-840 of the "Chemical Engineers
Handbook," 3rd Edition, McGraw-Hill. Also, vanadate
solutions other than ammonium decavanadate can be processed
such as :
Ammonium Metavanadate
Sodium Decavanadate
Sodium Metavanadate
Potassium Deca~anadate
Potassium Me~avanadate
The recovered vanadate product can be conventionally
heat decomposed to yield the industrially useful product V205.
-5-

57
Heating and gas flow arrangements other than
that shown in the drawing can be usPd in the practice of
the present invention such as Pxterior heating and
horizontal drying chambers and countercurrent gas flow
techniques known to the art.
, ., ;