Conveyors: fluid current – Slug conveying
Reexamination Certificate
2002-06-13
2003-10-21
Dillon, Joseph A. (Department: 3651)
Conveyors: fluid current
Slug conveying
C406S106000, C406S168000, C406S131000
Reexamination Certificate
active
06634832
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of and apparatus for transporting particulate materials from a lower level to a higher level, for example gold and other mined ores or construction debris.
BACKGROUND TO THE INVENTION
It is known to use pseudoplastic flotation fluids in the pumping of materials of suitable particle size, for example drilling debris in an oil well. While this technique might in theory be used to transport ores and other solids from the working level of a mine to the surface, rather than using conventional mechanical lifting gear, in practice the energy requirements are too great to make the technique a practical proposition.
In general the currently-utilised method of moving gold and other mined ores or construction debris to surface is by means of single or multi-stacked ore skips as hoisted by wire rope with surface located winding gear powered by whatever required motive force via purpose designed control equipment. This method has in passing to carry the non productive weight of the skips and their stacking frame plus the weight of the hoisting wire rope, with allowances for the overcoming of inertia and associated friction forces. A multi-skip hoist shaft can also require extra area over that for man-riding cages and equipment hoists as might be obviated if ore could be pumped to surface. Whilst it is known that ore at suitably ground down size can be pumped in a fluid of higher density than water so as to be able to hold the particulate in suspension, this imparts hydrostatic and surge forces on such pumps which increase with depth. Where a sudden stoppage in flow occurs, this can create at restart many time-consuming problems in such systems.
All metal mines and some civil construction works utilise water at their mining or rock excavation level, whether for the drilling of diamond cored mineral or rock samples or for general cooling and dust control from percussion drilling and blasting. The liquid residue of such methods can be utilised for the mixing of hydraulic ore hoist fluid as afterwards recycled within the working zone prior to any excess being pumped back to circuit or to surface from a gravity fed sump located at base of access shaft.
Background prior art is indicated by GB-A-2 047 818, GB-A-1 543 817, EP-A-0194 498 and US-A-5 069 583.
SUMMARY OF THE INVENTION
The invention provides a method of transporting particulate materials from a lower level to a higher level, comprising:
establishing a flow loop comprising a closeable chamber for receiving batches of the particulate materials, a first flow conduit extending upwardly from the chamber to a delivery level, a second flow conduit extending upwardly from the chamber to a header tank located at a higher level than said delivery level, and valve means at the chamber for selectively isolating the chamber from the first and second flow conduits;
filling the flow loop with a pseudoplastic flotation fluid;
operating the valve means to isolate the chamber from the first and second flow conduits;
introducing a charge of the particulate materials into the chamber and then closing the chamber;
operating the valve means to connect the first and second flow conduits to the chamber; and
maintaining a supply of fluid in the header tank such that fluid and entrained particulate materials flow from the chamber through the first flow conduit to the delivery level.
The invention also provides apparatus for transporting particulate materials from a lower level to a higher level, comprising:
a flow loop comprising a closeable chamber for receiving batches of the particulate materials, a first flow conduit extending upwardly from the chamber to a delivery level, a second flow conduit extending upwardly from the chamber to a header tank located at a higher level than said delivery level, and valve means at the chamber for selectively isolating the chamber from the first and second flow conduits;
a pseudoplastic flotation fluid filling the flow loop;
means for introducing a charge of the particulate materials into the chamber and means for closing the chamber; and
means for separating the particulate material from the fluid discharged at the delivery level and for returning the fluid to the header tank.
Thus, the invention provides for the transport of ores, minerals and the like in a stream of purpose designed flotation fluid by means of an upper and lower interconnected U tube with an ore loading chamber just below the base of the upper U tube, this and the lower U tube being controlled by a multi-function valve whose hydraulic jack components are able to utilise the same flotation chemical, preferably at a higher concentration, which can simultaneously lubricate all other moving parts of the valve apparatus for use in that method.
The ore loading chamber can be formed in situ as a rock pressure vessels. Also, the two limbs of the upper U tube can be formed as drilled holes at the edge of or beyond the edge of any mine or tunnel access shaft, preferably in a manner which allows the drilling bit to be removed from within its drilling drive tube to allow an onward sealed in situ use as the pressurisation and hoisting ducts to such an ore loading chamber. Such methods of formation are known from U.S. Pat. Nos. 4,950.034 and 4,878,549.
In considering the utilisation of a hydraulic method of ore or tunnel debris hoisting or horizontal transportation the further reuse of whatever water is existent at the salient location the primary objective where the continuous pumping of minerals of higher specific gravity than water poses not only the problem of their suspension during the pumping process but also their chemical compatibility with the purpose designed flotation fluid as mixed with water having whatever pH and minerals content. By the use of a double U tube to continuously eject ore in a stream of suspending biodegradable pseudoplastic fluid having a design able to accommodate wide ranges of pH and minerals content offers additional advantages:
the reuse of liquid run off from other in-mine systems;
the partial use as an ore lixiviant during its transportation phase;
can be utilised as the hydraulic fluid element of recycled treated ore as stowed mine fill with or without uncontaminated cementitious addition; and
also able to be diluted to water viscosity for general mine use.
Preferably according to the present invention there is provided a method of operating a chain linked high pressure valve apparatus at the intersection of an upper and lower U tube, comprising an outer multi-valve common housing with at least nine entrants one of which is fitted with a double cone type valve allowing the sequence tensioned movement of a chain of a type exhibiting zero elongation via a third unvalved internal entrant carrying a sliding section of the apparatus having three separated aperture alignment type valves as allow the double U tube system to eject either the ore in suspension or recycle the suspension devoid of ore where this element of cycle allows any desanding or chemical beneficiation. Also, at higher mine level or at ground level of a set of synchronised lower pressure standard valves is preferably provided, connecting into the top of the longer U tube limb to allow this to impart a larger hydrostatic head to that in shorter U tube limb, both limbs connecting to the flotation fluid pumping or gravity supply pipework such as to allow a cyclic operation via a closed pre-set pressure control loop. Alternatively, an open gravity-controlled overspill calibrated excess hydraulic head arrangement incorporates an open or closed fluid volume control funnel at top of longer U tube limb, where in the gravity-assisted case a reciprocal raising and lowering of a weighted vessel by use of a wire rope can effect control of volumetric symmetry between the longer and shorter U tube limbs as retains their pre-calculated differential head. Additionally, a secondary utilisation this wire rope can be used to open the gravity weight assisted cone valve in the lower level commonly-housed control apparatus, this be
Dillon Joseph A.
Watov Kenneth
Watov & Kipnes P.C.
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