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Friday May 28<LI class=stdlist>
(400k) Donald introduces his three guests from this morning's audioconference, held outside the melting plant, at New Zealand Steel's Glenbrook Mill.
(2.4mb) The electrodes that provide electricity for the melter are big. Not just big, huge. And there are six of them! In this video watch carefully and you'll see the electrode - yes that large cylinder next to Hoani - move slowly up and down. What is the current travelling between each pair of electrodes?
(2.4mb) High above the melter - on the same level as the electrodes - are containers that feed the melter with the reduced primary concentrate (RPCC). The RPCC is the reduced iron sand from the rotary kilns- now iron in a powder form along with char (carbon from the coal). This mixture is fed automatically into hoppers above the melter, in 20 tonne containers.
(1.6mb) Donald and Hoani are on the roof of the melter. Hoani describes what you can see: the electrodes, the gas offtake and the screw feeder body which feeds the reduced primary concentrate (RPCC) into the melter.
(1.4mb) On the metal side of the melter (the side the iron is taken from) Randall explains how the molten iron will be removed from the melter. The iron comes out of the tap hole and flows down the launder (a drain) into a ladle. Why is the gas flame being directed onto the launder?
(3.8mb) Stand back! Randall explains as the melter is tapped and molten iron flows into the ladle. During the process a sample of iron is taken, the temperature of the molten iron is taken, and the tap hole is lanced with pure oxygen. Eventually a kress appears to take the ladle to the weighbridge and then to the steel plant. How long does it take to fill one ladle?
(2.3mb) On the slag side of the melter (the side opposite the metal side) where slag is removed, Randall shows us how the tap hole is opened with a rock drill, to allow slag to drain down the short launder (drain) and into the bowl below, and then how the tap hole is closed with the mud gun.
(3.6mb) Dressed like Darth Vader, Randall manages the flow of slag down the launder into the bowl (below us). To unblock the tap hole Randall drives a lance into the hole blowing oxygen into the hole. Why does the molten slag not flow as well as molten iron? Finally Randall closes the tap hole with the mudgun.
(640k) The kress arrives to pick up the slag bowl. How fill is the bowl?
Thursday May 27
These first set of movies Step 1 to Step 11 show the process of making sponge Iron from primary concentrate (pure Iron sand) and coal (with lime). <LI class=stdlist>
(920k) A key ingredient for making steel is coal. It arrives right where Donald is standing, by train. Lime is dropped off here to. How many trains a day bring coal? How many bring lime? Where does the coal come from?
Grant Thompson Kiln Area Manager explains how lime and coal are mixed in these stockpiles, before being sent to the multi hearth furnace (MHF) be conveyor.
(1.2mb) Yesterday Donald saw the slurry pipe leaving the Waikato Head Mine. In the pipe concentrated Iron ore is pumped with water, 15 km here to the mill. Grant explains where the pipe goes to next and how the water is removed.
(860k) How simple! Here you can see the water being removed from the slurry leaving dry Iron concentrate now called Primary Concentrate (PC). What causes the water to be removed?
(650k) The water removed has to be cleaned before being returned to local streams. Here Grant explains how chemicals are added to make the muddy sediments (called slimes) stick together so they can be screened out. This is called flocculation.
(1.7mb) Grant shows us the huge stockpile of Primary Concentrate (concentrated Iron sand) that comes from the dewatering plant. Then Donald goes underneath the stockpile to where the PC is 'reclaimed' and sent by conveyor to the multi hearth furnace (MHF).
(1mb) Where would the Mill be without conveyor belts? Donald follows two large conveyors, one carrying coal+lime the other Primary Concentrate as they head for the Multi Hearth Furnace. However only one conveyor actually enters the very top of the Multi Hearth Furnace. Donald explains.
(1.6mb) You can't see the 12 hearths of the Multi Hearth Furnace (MHF) but you can see the hot pans on the conveyor carrying the Carbon, Calcium oxide and hot dry Iron oxide. The furnace gets very hot so a shower is available as a safety device. Grant checks it out!
(670k) Alister a Kiln Operator explains how the product from the pan conveyor (straight from the multi hearth furnace) is added to the top of the rotary kiln.
(1.6mb) Donald takes a walk with Alister along the walkway 15m above the ground beside the rotary kiln. What length is the kiln? What is the Iron oxide (dry sand) changed into during its passage through the kiln? What is the concentration of the pure Iron?
(1.4mb) At the end of the kiln temperatures are high. How high? The Iron at this stage is a fine powder that you can see falling down through the flames. The fine powder is called sponge Iron because every small particle, seen under a microscope has tiny holes in it.
(1.5mb) Dick Parsons explains that gases from combustion of coal are scrubbed to remove sulphides and other poisonous gases. How is this done?
(1.2mb) Debbie Bryson explains to Donald her responsibilities to monitor any effects of the Mill on the environment.
(1.5mb) Debbie explains what happens to the treated water before it is discharged into the Manukau Harbour. What percentage of water is recycled?
Wednesday May 26
(1.4mb) Donald asks Dick Parsons, Engineer and Mike O'Connell, Mine Manager to introduce themselves at the Waikato North Head Mine.
(1.3mb) Donald asks Mike O'Carroll to explain how the iron sand came to be at Waikato North Head. Where did the iron sand originate from?
(570k) Donald's guests Mike O'Connell, Mine Manager and Dick Parsons, Engineer answered questions from students at Hornby High School during the today's audioconference Where was Donald today?
(2.3mb) The start of the mining operation is at the coal-face - well sand face really!. How many tonnes of sand can the excavator mine in an hour? Mike O'Connell explains.
(1.7mb) The bucket wheel excavator is am impressive sight when in operation. The excavator sends sand to the first belt wagon then the second belt wagon then to the bench conveyor and on to the processing plant.How many conveyor belts can you see in use here?
(2.1mb) Mike O'Connell explains how the belt wagons help get sand away from the excavator and up to the conveyors to the processing plant.
(510k) Big machinery needs heaps of power! The excavators and belt wagons are electrically driven. What voltage arrives at the excavator? What voltage do the transformers reduce it to for use in the motors?
(550k) Mike O'Connell explains how the mining operation works through the old dunes. You can see the Tasman Sea in the distance.
(2.6mb) Donald gets close to a cross section of a sand dune created by the mining operation. How did this sand get here? Can you see evidence of this?
(1.8mb) Stage 2 of the ore concentrating process uses the fact that the iron materials are heavier than the waste materials (tailings).
(820k) Stage 3 of the ore concentrating process throws low grade material to the outside of the spiral and the heavier ore sticks to the inside. Simple eh!
(650k) Stage 3 of the ore concentrating process uses magnetism again to finally concentrate the ore before it ends up on the stockpile.
(870k) The concentrated ore (titano-magnetite) with the water removed, falls onto the stockpile. Beneath this huge pile is yet another conveyor that takes the sand to a mixing station where it is combined with water before the 18km journey through a pipe to the steel mill.
(1.6mb) Mike O'Connell explains what happens to the sand that is left after the iron ore is removed. Where does it go?
(560k) From the stockpile is a large lake. Mike explains that the lake is an important part of the mine site.
(1.4mb) Earlier in the day Donald held a handful of iron sand near a compass. The unprocessed sand shifted the compass needle about 2 degrees. What effect does a handful of concentrated iron ore from the stockpile have on the compass? How does it react to Donald's magnet?
(1.1mb) On the road between the North Waikato Head mine site and the Glenbrook steel mill are signs like this one. Donald asks Dick Parsons to explain the significance of the slurry pipeline - a world first.
(1.8mb) Mike O'Connell explains how the benches are created during the process of mining the iron sands. The huge machinery makes a new landscape, later to be backfilled with the mine tailings. Why does the bucket wheel excavator sometimes work more slowly? Why is the iron sand sometimes a reddish colour, other times a dark grey?