PATENT ABSTRACT
Apparatus for storing and dispensing flowable explosive, the apparatus including an explosive pump for pumping flowable explosive into an explosive tank having a fluid pressure-actuated piston movable therein for expelling flowable explosive out of the explosive tank through a delivery hose fitted with an injector through which one or more additives from one or more additive tanks can be pumped by an additive pump.

PATENT DESCRIPTION
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a mobile delivery platform for flowable explosive. 
       BACKGROUND OF THE INVENTION 
       [0002]    Flowable explosive, such as emulsion explosive, is conventionally delivered in surface and underground applications using gravity tanks. Gravity tanks have a high centre of gravity and are not easily transportable. They also require a top access structure for cleaning and maintenance of the inside walls to prevent crystallization of the emulsion explosive. The top access structure limits tank capacity and is a fall hazard for workers. 
         [0003]    A need therefore exists for a mobile, self-cleaning delivery platform for flowable explosive. 
       SUMMARY OF THE INVENTION 
       [0004]    According to the present invention, there is provided apparatus for storing and dispensing flowable explosive, the apparatus including an explosive pump for pumping flowable explosive into an explosive tank having a fluid pressure-actuated piston movable therein for expelling flowable explosive out of the explosive tank through a delivery hose fitted with an injector through which one or more additives from one or more additive tanks can be pumped by an additive pump. 
         [0005]    The explosive tank and the piston therein can be cylindrical with a common horizontal longitudinal axis. 
         [0006]    The piston can have one or more circumferential seals for cleaningly wiping the inner surface of the explosive tank. 
         [0007]    The piston can be a concave piston that is radially expandable to sealingly engage the inner surface of the explosive tank. 
         [0008]    The explosive tank can have a detector therein for detecting displacement of the piston and/or monitoring quantities of flowable explosive in the explosive tank. 
         [0009]    The one or more additives can be lubricant stored in a lubricant tank, and explosive additive stored in an explosive additive tank. 
         [0010]    The delivery hose can be wound on a hose reel. 
         [0011]    The tanks, pumps, and hose reel can be arranged on a transportable platform. 
         [0012]    The flowable explosive can be selected from emulsion explosive, gel explosive, slurry explosive, blended explosive, and doped explosive. 
         [0013]    The present invention also provides a method of delivering flowable explosive using the above apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will be further described by way of example only with reference to the accompanying drawings, in which: 
           [0015]      FIG. 1  is a schematic diagram of fluid circuit of an embodiment of a mobile delivery platform for flowable explosive of the invention; and 
           [0016]      FIG. 2  are side, plan and end view of the mobile delivery platform. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to the  FIG. 1 , an embodiment of a mobile delivery platform  26  for flowable explosive generally includes an explosive tank  1 , an explosive pump  10 , an additive pump  14 , an explosive additive tank  15 , a lubricant tank  16 , and a delivery hose  23  wound on a hose reel  22 . Referring to  FIG. 2 , these components are arranged together on a transportable platform  24 , for example, a multimodal transport platform with International Standards Organization (ISO) standardised multimodal attachments or fittings. 
         [0018]    The explosive tank  1  is cylindrical and is made, for example, of a corrosion resistant or a suitable pressure vessel material. The explosive tank  1  has a capacity, for example, of 3 tonne. A cylindrical piston  6  is axially movable inside the explosive tank  1 . The explosive tank  1  and piston  6  have a common longitudinal axis horizontal to the transportable platform  24 . The piston  6  is a concave piston that is radially expandable when pressurised to sealingly engage the inner surface of the explosive tank  6 . Two circumferential seals  7  are provided on the piston  6 . The piston seals  7  cleaningly wipe the inner surface of the explosive tank  1  during axial movement therein of the piston  6 . Together, the piston  6  and the piston seals  7  provide a “self-cleaning” action that prevents build-up of flowable explosive on the inner surface of the explosive tank  1 . Other equivalent “self-cleaning” piston and seal arrangements may also be used. The piston  6  is made of, for example, corrosion resistant material. The piston seals  7  and the delivery hose  23  are made of, for example, rubber. Together, the piston  6  and piston seals  7  sealingly divide the explosive tank  1  into opposed pressure and explosive ends. 
         [0019]    The pressure end of the explosive tank  1  is provided with an inlet manifold  5 , a pressure relief valve  2 , and a piston displacement sensor  4 . The pressure inlet manifold  5  includes a pressure regulator and a pressure gauge. The piston displacement sensor  4  is, for example, a laser detector. 
         [0020]    The explosive end of the explosive tank  1  is provided with a pressure relief valve  3  and a selector valve  8  to control flow of flowable explosive to and from an inlet/outlet port in the explosive tank  1 . The flowable explosive is, for example, emulsion explosive, gel explosive, slurry explosive, blended explosive, doped explosive, etc. The flowable explosive has a viscosity of between around 20,000 and 90,000 centipoise (cP), for example, 40,000 cP. 
         [0021]    Flowable explosive is drawn from an external supply (not shown) via selector valves  9 ,  18  by the explosive pump  10  and pumped via selector valves  11 ,  8  into the explosive end of the explosive tank  1 . This displaces the piston  6  backwardly toward the pressure end of the explosive tank  1 . The backward displacement of the piston  6  is monitored by the piston displacement sensor  4 . The pressure relief valve  2  acts as a bleed valve to maintain backpressure against the piston  6  so that it is positively retained next to flowable explosive pumped into the explosive tank  1 . A flow meter  12  is connected to the explosive pump  10  to indicate the flow rate of flowable explosive pumped into the explosive tank  1 . The explosive pump  10  is, for example, a high pressure diaphragm pump. 
         [0022]    Flowable explosive is discharged from the explosive tank  1  via the selector valves  8 ,  11  to the delivery hose  23  by applying fluid pressure to the piston  6  via the pressure inlet manifold  5 . The fluid pressure is, for example, air pressure from a source of compressed air, for example, a truck compressed air system. The air pressure displaces the piston  6  forwardly toward the explosive end of the explosive tank  1 . The forward displacement of the piston  6  is monitored by the piston displacement sensor  4 . The discharge pressure of flowable explosive is indicated by a pressure meter  13 . The delivery hose  23  is unwound from the hose reel  22  and positioned to deliver the flowable explosive from the explosive tank  1  to a surface or underground delivery site, for example, a blast hole. The delivery rate of the flowable explosive is, for example, up to around 1100 litres per minute. The flowable explosive is substantially fully discharged from the explosive tank  1  by the piston  6  as the “self-cleaning” action of the piston  6  and the piston seals  7  leaves less than around 0.05% by weight of the initial load of flowable explosive remaining in front of the piston  6 . 
         [0023]    The pressure required to discharge flowable explosive is selectively reduced by injecting flowable lubricant stored in the lubricant tank  16  into the delivery hose  23 . The lubricant is, for example, water, oil, polymeric lubricant, etc. The flowable lubricant is pumped from the lubricant tank  16  via selector valve  17  by the additive pump  14  to an injector  19  fitted to the delivery hose  23 . The pressure and flow rate of lubricant injected into the delivery hose  23  are respectively indicated by a flow meter  20  and a pressure meter  21 . The additive pump  14  is, for example, a piston pump. The lubricant tank  16  is filled with flowable lubricant via a filler or from an external source (not shown) via the selector valves  9 ,  18 . Lubricant, such as water, is selectively pumped by the additive pump  14  from the lubricant tank  16  through the explosive pump  10  for cleaning the explosive pump  10 , injector  19  and delivery hose  23  after flowable explosive has been discharged from the explosive tank  1 . A check valve between the lubricant tank  16  and the selector valve  18  prevents backup of water into the lubricant tank  16  during cleaning. 
         [0024]    Explosive additive stored in the explosive additive tank  15  is selectively injectable into the delivery hose  23  by the additive pump  14  via the selector valve  17 . The explosive additive is, for example, gassing solution. The explosive additive tank  15  is filled with explosive additive via a filler. The flow and pressure meters  20 ,  21  measure the flow and pressure of explosive additive injected into the delivery hose  23 . 
         [0025]    Referring to  FIG. 2 , a control panel  25  is provided at one end of the platform  24  for the flow and pressure meters  12 ,  13 ,  20 ,  21 , a display of the piston displacement sensor  4 , and controls for the explosive pump  10  and the additive pump  14 . The selector valves can be solenoid valves having controls provided in the control panel  25 . 
         [0026]    The mobile delivery platform  26  can form part of a mobile manufacturing unit (MMU), an underground delivery system, or a plant storage unit. 
         [0027]    It will be appreciated that embodiments of the invention advantageously provide a mobile, self-cleaning delivery platform for flowable explosive. 
         [0028]    The embodiments have been described by way of example only and modifications are possible within the scope of the claims which follow.