Agitating – Stirrer within stationary mixing chamber – Rectilinearly reciprocable stirrer
Reexamination Certificate
2002-11-15
2004-12-14
Soohoo, Tony G. (Department: 1723)
Agitating
Stirrer within stationary mixing chamber
Rectilinearly reciprocable stirrer
C366S316000
Reexamination Certificate
active
06830369
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the field of mineral ore processing, and more particularly, to a mixing apparatus and to uses thereof in the separation of minerals from mineral-bearing ores.
BACKGROUND OF THE INVENTION
Processes are known in the prior art which provide for the separation of minerals from mineral-bearing ores.
For example, in known processes used for the separation of copper from copper-bearing ores, illustrated diagrammatically in
FIG. 1
, non-oxidized ores
20
(which might contain as little as 0.5% copper, and typically contain iron sulfides) are processed in a crusher
22
, with water
24
, to form a slurry
26
. The slurry
26
is then transferred to a flotation cell
28
, and subjected to physical action, specifically, air sparging and mixing. As a result of the physical action, a substantial portion of the copper value in the slurry
26
rises to the surface of the flotation cell
28
as a froth
30
, and is skimmed therefrom by a paddle mechanism
32
, while the waste rock
33
(“gangue”) remains in the bulk, and is ultimately passed from the cell
28
to a dryer
34
and discharged as tailings
36
. This process of “froth separation” results from differences in wettability of copper as compared to other minerals, and is typically aided by chemical frothing and collector agents
38
added to the slurry
26
, such that the froth
30
from such flotation contains 27 to 36% copper. Methylisobutyl carbonal (MIBC) is a typical frothing agent, and sodium xanthate, fuel oil, and VS M8 (a proprietary formulation) are typical collector agents.
The froth
30
is then fed to an oxygen smelter
40
, and the copper and iron sulfides are oxidized at high temperature resulting in impure molten metal
42
(97-99%, copper, with significant amounts of iron oxide) and gaseous sulfur dioxide
44
. The impure metal
42
is then transferred to an electrolytic purification unit
46
, which separates the impure metal
42
into 99.99% purity copper material
48
and slag
50
.
The gaseous sulfur dioxide
44
is collected in a reactor
52
wherein it is scrubber and mixed with water
24
to form sulphuric acid
54
. The sulphuric acid
54
is suitably blended with water
24
and used to leach oxidized ores, typically by “heap leaching” an ore pile
56
. The resultant copper-bearing acid
58
is known as “pregnant leach solution”. Pregnant leach solution
58
is also obtained by mixing solutions of sulphuric acid
54
, in vats
60
, with the tailings
36
discharged from flotation operations, to dissolve the trace amounts of copper remaining therein.
The copper is “extracted” from the pregnant leachate
58
by mixing therewith, in a primary extraction step
62
, organic solvent
64
(often kerosene) in which copper metal preferentially dissolves. Organic chemical chelators
66
, which bind solubilized copper but not impurity metals, such as iron, are also often provided with the organic solvent, to further drive the migration of copper. Hydroxyoximes are exemplary in this regard.
In the primary extraction step
62
, the copper is preferentially extracted into the organic phase according to the formula:
[CuSO
4
]
aqueous
+[2 HR]
organic
→[CuR
2
]
organic
+[H
2
SO
4
]
aqueous
where HR=copper extractant (chelator)
The mixed phases are permitted to separate, into a copper-laden organic solvent
68
and a depleted leachate
70
.
The depleted leachate
70
is then contacted with additional organic solvent
72
in a secondary extraction step
74
, in the manner previously discussed, and allowed to settle, whereupon the phases separate into a lightly-loaded organic (which is recycled as solvent
64
in the primary extraction step) and a barren leachate or raffinate
76
.
The barren leachate
76
is delivered to a coalescer
78
to remove therefrom entrained organics
80
, which are recycled into the system; the thus-conditioned leachate
82
is then suitable for recycling into the leaching system.
The pregnant organic mixture
68
(produced in the primary extraction step
62
) is stripped of its copper in a stripping operation
84
by the addition of an aqueous stripping solution of higher acidity
86
(to reverse the previous equation); after phase separation, a loaded electrolytic solution
88
(“rich electrolyte”) remains, as well as an organic solvent, the latter being recycled as solvent
72
in the secondary extraction
74
.
The rich electrolyte
88
is directed to an electrowinning unit
90
. Electrowinning consists of the plating of solubilized copper onto the cathode and the evolution of oxygen at the anode. The chemical reactions involved with these processes are shown below
Cathode: CuSO
4
+2
e
1−
→Cu+SO
4
2−
Anode: H
2
O→2H
+
+0.5 O
2
+2
e
1−
This process results in copper metal
92
, and a lean (copper-poor) electrolyte, which is recycled as stripping solution
86
.
The combination of leaching, combined with extraction and electrowinning, is commonly known in the art as solvent extraction electrowinning, hereinafter referred to in this specification and in the claims as “SXEW”.
In a known application of the described SXEW process, in both the primary
62
and secondary
74
extraction steps, the combined organic and aqueous phases are delivered through a series of mixing vessels (primary P, second S and tertiary T), and then to a settling tank ST, the primary mixing vessel P being about 8 feet in diameter and 12 feet in height, and stirred by a rotary mixer driven by a 20 horsepower motor, and each of the secondary S and tertiary T mixing vessels being about 12 feet in diameter and height, and stirred by a rotary mixer driven by a 7.5 horsepower motor. (The system of primary P, secondary S and tertiary T mixers, and settling tank ST, is replicated to meet volume flow requirements, with each system processing about 10,000 gpm). This provides a mixing regime wherein the organic and aqueous phases are intimately mixed for a period of time sufficient to allow copper exchange (to maximize copper recovery), yet relatively quickly separate substantially into organic and aqueous phases.
In a known application of the froth flotation process, a plurality of flotation cells
28
, each being approximately 5 feet square and 4 feet high, are utilized, with pairs of cells sharing a 50 horsepower motor driving respecting rotary mixers (not shown). This provides a mixing regime sufficient to allow the air bubbles to carry the copper value to the surface.
Various modifications can be made to the rotary mixers in the extractors and in the flotation tanks of the foregoing process. However, the general configurations noted above have been found to provide relatively economical results, and significant variations therefrom can impact adversely upon economies. For example, an attempt to reduce energy costs by scaling-down the motors for the mixers would have consequent impacts either upon the copper recovery efficiency, or upon available process throughputs. Specifically, the relatively large motors employed are required to drive the sturdy (and therefore heavy) rotary mixers and shafts that are needed to withstand the torques caused by rotation; lower power motors would demand either lower blade speed or smaller blades, with consequent impacts upon mixing and transfer efficiency.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel mixing apparatus.
This object is met by the present invention which comprises a mixing apparatus. The mixing apparatus is advantageously used with a vessel having a contiguous sidewall centered about and defining a longitudinal axis.
As one aspect of the present invention, the mixing apparatus comprises a mixing head having a tubular blade portion centered about and defining a head axis and having a first tube end and a second tube end spaced-apart from one another therealong.
The blade portion tapers from the first tube end to the second tube end with the inner surface of the blade por
Behr Martin
Haughton Gary
Ostrowski Tom
Enersave Fluid Mixers Inc.
Hofbauer Patrick J.
Soohoo Tony G.
LandOfFree
Mixing apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mixing apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mixing apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3319167