AU2005248954B2 - Rock drill water separator - Google Patents

Description

1 ROCK DRILL WATER SEPARATOR Field of the Invention The present invention relates to rock drill dust suppression apparatus and in particular to a unit adapted to sit behind the drill bit and separate water from the composite air and water stream commonly directed through rock drill strings towards drill bits. Background of the Invention Typically rock drills such as are utilised to create bores in which to place explosive charges comprise a drill bit mounted at the forward end of a drill string which string consists of sections joined together by appropriate connectors. In order to assist in evacuation of debris created by the action of the drill bit on the rock air is delivered at high pressure through a bore of the drill string to the drill bit. This air then exhausts with debris back up the hole being created by the drill between the drill string and the sides of the hole being drilled. Typically this evacuation of debris laden air creates enormous volumes of dust which adversely effect the environment, workers and mechanical equipment. Consequently it has been found to be desirable to inject water into the air and debris exhausting from the cutting face. It is practical to deliver the water and air together down the centre of the drill string to the area adjacent the drill bit. Whereas it is important that the air reaches the cutting face at the front of the drill bit is undesirable that water be delivered to the front of the drill bit as this produces a slurry which causes wear on the cutting services of the drill bit and furthermore creates corrosion difficulties for the bearings and components in and adjacent the drill bit. Typically therefore apparatus exists, such as that described in US Patent 5927439, for separating the water and air flow in an assembly just behind the drill bit to facilitate delivery of the air to the drill bit and evacuation of the water from the interior of the 2 drill string to the exterior of the drill string just before it reaches the vicinity of the drill bit. Object of the Invention Existing dewatering modules which are installed at the end of the drill string and behind the drill bit are complex, expensive and to some extent inefficient and it is consequently an object of the present invention to ameliorate one more of the above mentioned disadvantages with existing dewatering units or at least to provide the market with an alternative. Short Summary of the Invention According to the present invention there is disclosed a dewatering module adapted to be inserted between a rock drill bit and a drill string comprising an outer housing and having a first end remote from the drill bit and a second end adapted to lie immediately adjacent the drill bit; an air/water inlet at the first end of the module adapted to receive a high pressure composite air and water flow from within the drill string and to deliver said flow into a main chamber within the module; an inner tubular housing within the chamber defining a passage within the chamber from its first and inlet end adjacent the air/water inlet to its outlet and second end at the drill bit; the first and inlet end of the inner housing being shielded by a first baffle from the composite air water flow entering the chamber; the first baffle comprising a deflector overlying the first and inlet end of the inner housing and having a skirt being of larger diameter than the tubular inner housing inlet such that air entering the inner housing is forced to reverse direction and traverse an "S" shaped path to enter the inner housing before traveling therethrough to the drill bit; a second laterally extending separator baffle beneath the skirt of the first baffle located such that and being of a diameter adequate to prevent direct entry into the inlet of an air/water stream deflected from the base of the main chamber upwardly towards the inlet of the inner housing; holes in the sides of the outer housing remote from the air/water inlet and baffle and adjacent its second end to facilitate evacuation of water from the chamber and into the area where debris from the drilling operation is being exhausted.

3 Brief Description of the Drawings One embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional view through a dewatering module in accordance with the present invention and Figure 2 is a second longitudinal sectional view through a dewatering module in accordance with the present invention. Preferred Mode of Carrying out the Invention According to the embodiment of Figure 1 there is disclosed a dewatering module 1 comprising an outer tubular housing 2 and an air/ water inlet 3 adjacent first end 4 thereof. The second end 5 of the module is adapted to receive a drill bit (not shown) in a standard mount 6. The module 1 defines a chamber 7 which in turn contains an inner tubular housing 8 extending from a first inlet end 2 to a second outlet end 10 adjacent the drill bit (not shown). The inlet end 9 of inner tubular housing 8 is covered by baffle 11 comprising conical hat portion 12 and depending skirt portion 13. It will be observed that the diameter of depending skirt 13 is greater than that of the inlet 9 to inner tubular housing 8 hence allowing passage of air between the skirt and the outer and upper extremities of tubular housing 8. In use the module operates by receiving a pressurised air/water flow through inlet 3 in the direction indicated by arrow 14. This flow is directed onto the centre of conical baffle 11. The inertia of the water contained within the flown causes the water to continue down a path indicated by arrow 15 which direction is deflected and modified by the baffle but is not the same as the path of the majority of air in the flow which air 4 traverses a path indicated by arrows 16. The lighter air is able to traverse the "S" shaped path necessary for the air to enter into tubular housing 8. Since the tubular housing 8 has a large outlet 10 adjacent the drill bit (not shown) it remains at lower pressure than the inlet air. Separation of air and water flow is therefore achieved. Water then exits the module via holes 17 in the outer housing 2 due to the centrifugal force of the rotating module forcing the relatively heavy water to the outside of chamber 7. The inlet 9 of the inner tubular housing is formed into a supplementary baffle by reason of it being shaped as an upwardly facing frustro-conical extension to tubular housing 8. The inlet 9 is hence of greater diameter than the tube and lesser diameter than the inside of the skirt 13 of the first baffle 12. The purpose of the inlet 9 being formed as a supplementary baffle is to help prevent reflected water and water spray from entering the inlet of the tubular housing 8 . It will be noted that this embodiment additionally includes second baffle 18 the purpose of which is to help prevent water and water spray from entering tubular housing 8. The second baffle is formed as an downwardly facing frustro-conical extension laterally extending from the inner tubular housing at a position below the skirt of the first baffle and of a diameter equal to or greater than that of the skirt of the first baffle; the purpose of which second baffle is to help prevent water and water spray from entering the inlet of the tubular housing. To achieve this purpose it must be located fairly close to the lower extremity of the skirt of the first baffle. Ideally a grating 19, removable so as to facilitate cleaning, may be incorporated in inlet 3. The grating serves the purpose of filtering and ensuring that the water entering the module contains no large particles which may clog the module hence rendering it inefficient or inoperative. Ideally the grating should catch particles of a size greater than 0.5 mm in diameter or of a size equal to or greater than holes 17. It will be appreciated that alternative embodiments of the present invention may be devised 5 apart from that example described above without departing from the scope and internment of the present invention.