Four years ago we were invited to Rocktec’s engineering workshops in Matamata to see the early design of a new vertical shaft impact crusher and screen made for Stevenson’s Drury quarry when it commissioned a $7 million aggregate processing plant with the Kiwi-made VSI crusher at its core. The set up was featured in Q&M in the December 2015 issue and can be read in full here: bit.ly/DruryQuarry
Since then the company has built two more. One of them was hauled out of the yard on Q&M’s visit last month while the third was being built in the workshop.
Both were made for client Stevensons Quarries (now Stevenson Construction Materials), with one going to Drury and the second one going to Stevie’s Huntly quarry.
“At Drury we’ve built a new plant where the old block plant was,” says Jason Tapper, Rocktec’s technical design and sales manager.
“We reused the old hopper, and then built a new plant out from there.”
Huntly has been preparing site works for a new plant, near the pug mill, also built by Rocktec.
Jason says the company took a different direction building the plant than it did with the first plant at Drury.
“We did a lot more assembly in the workshop and then sent big chunks to site. We designed the structures so it was all very similar in size; in fact all 16 x 5 [Rocktec Avalanche] screen structures are identical. We’ve also sold them a Terex Cedarapids 20 x 8 horizontal – a big triple deck horizontal screen.”
Rocktec also took an innovative approach to the foundations for this new equipment.
“Instead of having a skid frame, we used a big precast concrete slab with a steel frame around it. It is full of reinforcing and we had the concrete poured at a pre-cast factory on our border and they simply lifted it over the fence.
“The bolting to the frame is all the same though, so it becomes modular. The top section and bottom section [on top of the slab] were sent to site on the same truck.
“The foundation was sent with the complete screen structures with the chutes tucked in there as well.
“At the site we only have to complete a few lifts – the foundation and the first half of the structure in place in one lift, and then the top half of the structure on top of that. Sixteen bolts later and the complete support structure is in place.
“The stairway, travelling inside the chute, is attached with two more bolts and now we’ve got walking access around the whole thing with three lifts within one day.”
And time onsite costs money, adds Jason.
Streamlining the building of the new plant also involved making all the stairs the same, and all heights the same.
“We were then able to get the designers to focus on the chute work because that’s really where the magic works.”
The modular approach means that in five or 10 years’ time if the quarry wants to make a different product or add anything to the plant it can.
“We can just take that one chute segment out and put in a different one that sends to a conveyor elsewhere, or we can put a different segment in with a flop gate and a splitter.
“It’s designed to last and be future proof in terms of function.
“The old fix plants are set up to do XYZ, and that’s it, and anything that you want to change becomes more complicated.”
Jason says while there was a trend towards mobile plant for a few years he’s noticed an increasing demand for fixed plants.
“There’s more serviceability in a fixed plant. To change and maintain the rollers in a plant conveyor is a very simple process, and it’s got all that nice wide space to walk around for changing the screen media.”
Rocktec also built the structure for a Metso cone crusher (GP330) supplied to Huntly.
“We built a concrete slab, which is neat and tidy and can be hosed off. If needs be they can also use a little bobcat to clean up spill around the edges as it won’t damage the concrete because of the steel on the outside.”