mine dewatering by borehole submersible...


1. OVERVIEW Mine dewatering using submersible pumps is an efficient, low maintenance and reliable method to dewater an underground mine. They are not affected by underground constraints such as ventilation, power outages and inspections by personnel. Borehole pumps are usually remotely located from main surface infrastructure, and as such are fully automated.

A properly sized pump and motor, with a carefully designed underground sump, can dewater and control the underground mine waste water without the need to have underground personnel or large infrastructure installed underground.

From a mining aspect, careful positioning of the sump, and designing the sump to maximize water storage capacity, can provide a cost effective way to collect mine water by using gravity to drain the mine without the need for multiple underground pumping installations to be installed.

2. AQUA ENERGY GROUP SOLUTIONS Aqua Energy Group was founded to satisfy the mining, industrial and other power consumers need for the highest quality products available. We work with the customer to design, manufacture, install and commission customised equipment that is specified or required. Our team is comprised of friendly and experienced personnel who have worked in manufacturing and electrical engineering for many years. We can offer a turnkey project that removes the risk of having multiple suppliers supplying multiple items, that then have to be assembled and managed by mine site personnel.

3. OVERALL SYSTEM PORTIONS Aqua Energy Group offers a “whole of system” pumping solution. We have found it a most effective and economic solution when a mine installs the borehole, main power supply (HV aerials) and delivery pipeline, and we then connect that infrastructure to our system. Our system is easly broken into a mechanical portion and an electrical portion.

The mechanical portion comprises the whole of works within the bore-case (motor, pump, riser pipes, sensors and cables), the surface pipework and the connection to the surface delivery pipeline. The surface pipework consists of bore-cap elbow, pressure relief valves, pressure monitoring points, non-return valve, gate valve, sufficient pipework and stands to fit and support the above equipment, including the correct lengths for obtaining laminar flows for the flow meter.

The electrical system consists of all equipment required to connect to the mains power supply, transform the power to the pump operating voltage (typically 1100 volts), control and monitoring. On the larger drives, we use a soft start / soft stop to control the energies of the moving water, PLC control and HMI to allow for full control and monitoring of the pumping system.

4. NSW VS QLD DIFFERENCES NSW and QLD coal mining legislation differs on how an electrically powered borehole pump systems are to be assessed when considering explosion protection.

IN NSW the borehole pump system requires assessment and certification by a testing authority as explosion protected, usually as Exs. This approach introduces considerable control features, such as pre purging, gas monitoring and pressurisation.

In QLD, the legislation states the borehole, whilst ever it has water separating the borehole atmosphere from the mine atmosphere it is an NERZ zone.



Aqua Energy Group has a belief, based on an assessment of risk, as we have done elsewhere in Queensland, is to consider that although the borehole is an NERZ environment, it may be possible that the water plug underground covering the borehole may lower (naturally or otherwise) to a point where the NERZ ceases to apply. Our proven design incorporates a system of back to back protection layers that will remove power from the pump before that happens. Furthermore, the equipment that is powered in the borehole whilst the motor is not powered (e.g. motor RTD’s and water level sensor) are intrinsically safe. This ensures compliance to the coal mining regulations.

5. CURRENT & PAST PROJECTS This list, although not comprehensive, shows some of our history. Wambo Borehole Pump No:1 180m, Layflat suspension, ExP; Wambo Borehole Pump No:2 180m, Layflat suspension, ExP, 92% CH4 controlled, 1000v, 132kW, 40 l/s; United Borehole Pump No:1 Supervision, installation, commissioning, 240m, 230kW, 1000v. ExP, 50 l/s; United Borehole Pump No:2 Supervision, installation, commissioning, 240m, 230kW, 1000v. ExP, 50 l/s ; United Borehole Pump No:3 ExP Audit. 240m, 230kW, 1000v, 60 l/s; Liddell OC A few smaller pump installations, recovery, re-commissioning, layflat, 60kW; Liddell UG Triple installation, audit, fault finding and system repair Dartbrook Borehole Pump Relocation overview, auditing & compliance checking, ExP; Teralba 440m deep. Did not eventuate. Assistance to DMR on approvals process; Ashton Pump No:1 Design, installation, approvals, commissioning, 90m, 185kW, 1000v, ExS, 47 l/s; Ashton Pump No:2 Design, installation, approvals, commissioning, 130m, 185kW, 1000v, ExS, 52 l/s Oaky Creek (TG26) Engineering supervision of re-installation of a site pump, 45kW, flex main, 415v Oaky Creek No:1 (MG25) Design, installation, commissioning, 240m, 230kW, 1000v, 64 l/s; Oaky Creek No:1 (MG25.2/1) Design, manufacture, installation, commissioning, 240m, 550kW, 1000v, 132 l/s; Oaky Creek No:1 (MG25.2/2) Design, manufacture, installation, commissioning, 240m, 550kW, 1000v, 132 l/s; Oaky Creek No:1 (MG25.2/3) Design, manufacture, 240m, 550kW, 1000v. (awaiting installation), 132 l/s. Ulan Coal Management of Certification Process, dual borehole 275kW, ExS Awaba Tender stage (40m deep, 30kW) Moranbah Coal (in progress) Design, manufacture, installation, commissioning, 345m, 1050v, 40 l/s;

The above projects were various combinations of design, manufacture, project management, supervision, installation and commissioning. The Oaky Creek triple 550kW pump installation was designed, manufactured and installed in 8 weeks. The original installation was the MG25 project. About a year later the mine ran into water problems and an urgent fix was required. The MG25.2 project consisted of three x 550kW units on a 10 inch (250mm) rising main to work in conjunction with the 230kW unit. The first was installed in 8 weeks, the second 4 weeks later. The third was put on hold as control over the water make underground had been achieved. The four installed pumps had a designed pumping capacity of just under 500 litres per second. Part of this expansion project also required a power system analysis to determine if the expansion could be tolerated on the existing HV aerial power system.



6. GAS CONTROL As mentioned earlier, the management of gas in a borehole pump installation is easily controlled in NSW. In a QLD installation, consideration should be given to assessing the risk of encountering gas from the water. This may result in gas at the well head area, (requiring careful selection and location of electrical devices), and / or at the delivery end of the pipeline. These are simple fixes, but should be included in the design assessment process.

7. PUMPSET SELECTION We will determine the best pumpset required to carry out the specified duty. In order to determine this, we request a number of operating parameters that the pump must perform to. These parameters start with the basic:

1. How much water is required to be moved? 2. What is the seam to surface height? 3. What is the surface delivery distance and contours? 4. What is the type and size of the surface delivery pipe? (We can calculate & supply as well); 5. What power supply is available (415v, 1000v, 11,000v)? 6. What is the water quality? 7. What is the urgency?

Items 1 to 5 allows the design of the pump set, calculate the motor power required, determine riser pipe size and calculate the starter size and method of starting. Item 6 determines the materials used in the motor and pipes; and Item 7 determines the delivery times, which may mean the difference between a lesser quality pumpset to a better quality pumpset. A lesser quality pumpset means that there is an earlier delivery along will be an earlier increase in maintenance costs. The higher the quality, the better the reliability, the better the life expectancy, but as a down side, a longer delivery time.

8. DEEP OR SHALLOW? Surface to seam depth varies with all mines. The distance from the surface to the seam governs the type and size of pump, as well as the method by which water is transported from underground to the surface.

Simply put:

A Shallow Seam • can use a flexible rising main (similar to a heavy duty fire hose); but quality of manufacture is

important. A failure of the hose can mean a pump set dropping into the mine, or we can use a steel rising main.

• can use a submersible pump, or use a line shaft pump (motor is on the surface, pump is underground, connected by a drive shaft)

A Deep Seam • use a steel (galvanised or stainless) rising main, and a submersible pump.



9. RISER PIPES The selection of riser pipes is critical to the structural integrity of the installation. The pipes provide the strength to support the suspended system, as well as providing support for the power cables and other cables running underground, and a means to transport the water out of underground.

Over the years we have refined the design of the riser pipes, with features including the gusseting of the flange to improve strength, the flange itself being of oversize thickness compared to a standard table flange, and the gasket compression face designed to have maximum pressure per unit area over the gasket contact surface. A typical flange for a DN150 pipe and a DN250 pipe are shown below.

Typical 150mm Riser Pipe Flange Typical 250mm Pipe Flange

10. WATER LEVEL CONTROL The water level is monitored by an intrinsically safe pressure sensor, positioned directly above the non-return valve of the pump-set. This pressure sensor is sized for expected water depth, and outputs a 4-20mA electrical signal directly proportional to water pressure. This is then converted to water depth in the PLC, and when calibrated against the installation data on Relative Levels (RL’s) gives an accurate measurement of water level underground.

Some sensors can be fitted with a temperature sensor. This has been useful where the water temperature can be related to goaf temperatures, and to provide an indicator of temperature increases within the goaf due to spon-com.

11. ELECTRICAL SYSTEM Aqua Energy Group designs, manufactures, installs and commissions the entire system. We can connect to an existing low voltage supply, to an 11,000 volt supply, or any other supply voltage. The entire starter / transformer can be configured to any design requirements that the mine requires. Our flexibility is that we do not mass produce starters, we manufacture according to the individual need of the location.

We incorporate power load flow and fault analysis to each starter, and all items of equipment are designed to work in conjunction with the pump and motor arrangement.

We also build underground pump starters. Shown below is a recent 11,000/415v quad VSD pump starter, with associated sump pump and mixers.



12. INSTALLATION & COMMISSIONING Aqua Energy Group’s installation and commissioning processes and procedures ensure the capture of an accurate record of what is installed on the surface and in a borehole, the resultant depths, the performance confirmation during commissioning and the overall full functionality of the installed infrastructure.

13. TRAINING Because borehole pump systems have unique complexities to them, we provide training packages to enable mine site personnel to understand the installation, and how to respond to changing needs (eg water levels) as and when required.



14. PHOTOS

Cable Anchor on 150 Riser

Installing 230Kw Pump

150 Surface well head pipes

200mm Well head elbow

Installing Flexible Rising Main Pump NSW Installation


mine dewatering by borehole submersible...

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