Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR PRODUCING A BULK CONCENTRATE
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. national phase application of a PCT
application
PCT/RU2009/000456 filed on 8 September 2009, published as W02010/036143, whose
disclosure is incorporated herein in its entirety by reference, which PCT
application claims
priority of a Russian Federation patent application RU2008/138814 filed on 29
September
2008.
FIELD OF THE INVENTION
[0002] The invention relates to methods of producing the concentrate being
enriched for
precious metals recovery from clay-salt residues (slimes) of plants processing
potassium-
magnesium ores and rock-salt by the methods of pyro- and hydro-metallurgical
processing.
BACKGROUND OF THE INVENTION
[0003] From the technical viewpoint there are known methods of material
dewatering
(dehydration) which are close to the invention (Reference book on ores
enrichment. Special
and auxiliary processes, Moscow, publisher "Nedra", 1983, pp.77, 78, 96-98,
100, 102, 108,
109. A.A. Abramov, S.B. Leonov. Non-ferrous metal ores enrichment, Moscow,
publisher
"Nedra", 1991, pp.35, 37). These methods include dewatering of materials of
various lump
sizes in classifiers, filtering centrifuges, vacuum filters, press-filters,
drying ovens, etc. The
aforesaid methods are intended for maximal separation of liquid phase from
solid phase for
materials of a certain lump size. However, each of these methods taken
separately is not
intended for separating the liquid phase of "slimes" due to the complexity and
peculiarities of
substantial and granulo-metric composition of the material. It is known that
more than 70%
of the material has a lump size less than 0.1 mm and more than 20% of the
material has a
lump size less than 0.044 mm. Thusly, during the use of filtering centrifuges
providing
residual humidity less than 5% at the material lump size more than 1 mm, in
our case, some
portion of the material will transfer into the filtrate together with a
portion of useful
component.
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[0004] For the same reason, press-filters cannot be used. The use of drying
ovens is
impossible without a preliminary dewatering. Therefore, for dewatering of
slimes after the
centrifuging, a set of methods is necessary for dewatering carried out by
several apparatuses.
[0005] There is known a method of concentrate production from clay-salt
residues of
enterprises, processing potassium-magnesium ores and rock-salt, for recovery
of precious
metals (Russian Federation Patent # RU2256504 published on July 20 2005). This
method
includes at least a two-stage hydrocyclone treatment of slimes with the
extraction of
concentrate. Hydrocyclone treatment is carried out in two or three stages and
the concentrate
of hydrocyclones is a solid phase of insoluble residue of the slimes.
[0006] Initially, the slimes with a solid-to-liquid (S:L) ratio of 1:3 are
delivered for the
hydrocyclone treatment. At a first stage of the hydrocyclone treatment the
following
operations are carried out: - extraction of concentrate in the form of
insoluble residue coarse
fraction, - discharge of the hydrocyclone treatment first stage product in the
form of insoluble
residue fine fraction and salt solution. Then the first stage product is
processed into pulp with
a (S:L) ratio of 1:8, and is forwarded for re-cleaning on a second stage of
the hydrocyclone
treatment with an extraction of the concentrate in the form of residual
fraction of the slime
insoluble residue and a discharge of the hydrocyclone treatment second stage
product in the
form of salt solution with the subsequent joining of the concentrates
extracted by the
hydrocyclone treatment. In case of a high residual content of insoluble
residue in the
hydrocyclone treatment second stage product, an additional third stage of the
hydrocyclone
treatment is carried out, therefore the slimes of mineral-salt production
plants and flotation
plants are processed.
[0007] A disadvantage of this method is a high enough content of moisture and
impossibility to carry out the further pyro- and hydro-metallurgical
processing.
[0008] A method of concentrate production from clay-salt residues of plants
processing
potassium-magnesium ores and rock-salt according to patent RU 2284221
(published on
September 27, 2006) is also known. This method includes hydrocyclone treatment
carried
out in three stages; collective concentrate of the hydrocyclons treatment
(pulp) is a solid
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phase consisting of sedimentary and floating part, represented by residue of
slimes insoluble
in water and the liquid phase.
[0009] The pulp has the (S:L) ratio = 1:1 (solid and liquid phases) and the
residual content
of salts of K and Na is no more than 15%.
[0010] A disadvantage of this method is a high enough content of moisture and
impossibility to carry out the further pyro- and hydro-metallurgical
processing.
[0011] The proposed invention resolves the issue of pulp transformation after
hydrocyclone
treatment into an enriched concentrate in the form of dry granules with a
diameter from 8 to
15 mm, suitable for pyro- and hydro-metallurgical processing, which retains
all the properties
of primary slimes, i.e. all the content sum of precious metals and a content
of 20+5% of salts
in the solid state.
[0012] To achieve the aforesaid technological result in the inventive method
of collective
concentrate production for recovery of precious metals including a three-stage
hydrocyclone
treatment of slimes with the extraction of collective concentrate, the
collective concentrate,
being a mixture of sedimentary and floating materials with a (S:L) ratio of
1:1, is dewatered,
pre-dried, granulated, and it has the following distinctive features: the
concentrate is
demineralized (salts removal) until the salt content is 20 5%, granulated till
the granules
reach a size of 8 or 15 mm, dried till the humidity is 0.5%.
[0013] The distinctive features which make the proposed method different from
the
method, described as "the closest", are the following: collective concentrate
produced after
the hydrocyclone treatment, being the mixture of sedimentary and floating
material with the
(S:L) ratio = 1:1, is dewatered, pre-dried, granulated, then dried.
[0014] Due to these features, the inventive method allows for obtaining not
just pulp with
the (S:L) ratio = 1:1, but a collective concentrate, i.e. granulate containing
(remaining) a base
amount of sedimentary and floating materials, as well as natural and
technogenic organic
substances having significant fractions of precious metals.
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[00151 The proposed method contemplates the deployment of equipment for
gradual
separation of moisture to a threshold allowing for granulation with the
attaining of granules
having a diameter from 8 to 15 mm with the following after-drying up to a
moisture of 5%
with keeping all qualities of the initial slime, including natural and
technogenic organic
substances.
[00161 The results by this method are: a maximal saving of the non-soluble
residue of
slimes, natural and technogenic organic substances, and obtaining concentrate
in the form of
granules with a humidity of 5%, a granule diameter of from 8 to 15 mm, and a
remaining
content of salt of 20+5%. The insoluble residue is a concentrate containing
compounds of
Au, Pt, and Pd, having a mineral base (in a descending order): anhydride,
dolomite, quartz,
feldspar, chlorite, hydro-mica, hydroxides of Fe, sulphides, and organic
materials represented
by natural and technogenic substances.
[0017] For obtaining the concentrate it is necessary:
1. To provide removal of excessive moisture by means of centrifuging after
drying in auger
furnace and subsequent granulation.
2. In the process of granulation and drying in drum-type furnace to obtain a
concentrate with
the salt content of 20+5% and granule size of from 8 to 15 mm for subsequent
pyro-
metallurgical processing.
[00181 The method is carried out in the following way. After hydrocyclone
treatment, pulp
(pre-concentrate) is forwarded to a centrifuge where the whole of insoluble
residue while the
whole set of components transfers into agglomerated cake, and the salt
solution transfers into
centrifuge effluent. Then the cake is forwarded to an auger furnace where the
material is
finally dried to a humidity of 15%.
[00191 Then the material with the humidity of 15% is forwarded to a die-type
granulator for
granulation, from which it is discharged in the form of granules with the
diameter of from 8
to 15 mm, after which it is forwarded to a drum-type furnace for final drying
to a humidity of
0.5%.
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[0020] The need of creating such production sequence is stipulated by the fact
that the
pyro- and hydro-metallurgical processing is possible in the form of granules
with the
diameter of from 8 to 15 mm and the salt content of 20 5%.
[0021] The collective concentrate from clay-salt wastes of industrial plants
processing
potassium-magnesium ores and rock-salt, used in the process, is the slimes of
mineral-salt
production plants and flotation plants with a pulp density of 1.3 g/cm3 and a
(S:L) ratio = 1:3.
[0022] A distinctive feature of the concentrate is the following: a high
content of organic
substance represented by natural and technogenic substances (amines and
polyacrylamide).
It's worth to note that for the mineral-salt production plants the organic
substance content
(total) doesn't exceed 1.5%, while in our example the total content of organic
substances has
reached 3%, which is associated with including of an amination, at the stage
of vacuum
crystallization in the mineral-salt production process. This provides the
entering of amines
into the slimes and facilitates blocking and aggregation of the precious
metals organic
compounds.
[0023] The second distinctive feature is the need of concentrate production in
the form of
granules with the diameter is from 8 to 15 mm and the residual salts content
is 20 5%.
