Rotowaro Mine is situated on 2423 hectares west of Huntly, producing 1.3 million tonnes of coal per year, making it the 2nd largest opencast mine in New Zealand. The mine was established in 1978, and is projected to run until 2018. Stevenson Mining recently took over the operations in 2011, and has a positive outlook for the future.
The mine is active 20 hours a day 6 days a week, and employs over 100 site personal.
From June-13 to the year to date Rotowaro Mine moved over 21 million Bank Cubic Meters (BCM) of waste and 3.3 million tonnes of coal.
The majority of the coal is bought by the Glenbrook steel mill and Genesis Power, with the remainder of the coal going to North Island private home and industrial heating markets. Genesis Power Ltd. uses the coal to power the Huntly Power Station.
Rotowaro outsource the blasting to Orica Ltd to guarantee safe, accurate and reliable blasts. Orica use computer technology to program each detonator with a delay time to ensure maximum results are achieved as well as safety.
Once all the detonators are programed, the blasting system will double check the shot to make sure everything is operating as it should. Once the system has checked everything is functional only then can the shot be fired remotely away from the blasting site. The remote detonation ensures that nobody is compromised in the blasting process and everyone is a safe distance away. Inline Drilling are contracted to drill all the blast holes.
The Coal is extracted from the pit and carted along the haul road to the infeed hopper at the blending plant. However if the coal has too much waste in it, it has to go through the wash plant.
At the wash plant the coal and waste is separated; then the cleaned product can be carted to the blending plant.
At the blending plant the coal is put through a crusher and is sorted into piles depending on its quality. The coal is then placed into load-out bins which feeds the trains and trucks, which then is used to transport the coal to the end user.
The Blending plant crushes, sorts and loads the coal onto trains and trucks. Once the coal enters the blending plant it enters a rock crusher that crushes the coal into smaller pieces.
After the coal has been crushed a conveyor belt then transports the coal through a radioactive source that analyses the coals ash, sulphur and moisture content and then stockpiles the coal according to its ash content.
Once the coal has been stockpiled it is then placed into feeder bins which the blending plant operator mixes to create the correct ash content for the end user. Once the operator achieves the correct blend it is stored in a silo which fills the trucks and trains as they pass underneath.