Vision combines conservation with technology

The South Island of New Zealand is one of the most pristine environments on Earth: crisp, clean air, emerald green pastures, vivid blue rivers with crystal clear water and snow-capped mountains – a picture of paradise.

Life in the island’s capital city of Christchurch seems tranquil and unrushed. People there are polite and friendly and they actually respect the speed limit. But a visit to the city’s central business district is a stark reminder that things haven’t always been so tranquil.

Already weakened by a 7.1 magnitude earthquake in 2010, the city was struck by a 6.3 magnitude earthquake on 22 February, 2011. As well as causing widespread damage to buildings, roads and infrastructure, the quake tragically claimed 185 lives.

This disaster was compounded by two additional earthquakes, in June and December of the same year. More than 100,000 homes were damaged, many of them later condemned. More than two-thirds of the shops, hotels and office buildings in the heart of the city had to be demolished. The devastation was so widespread it took nearly two years to fully quantify all the damage. Early in 2013 the New Zealand Government announced the total damage estimate, a staggering $NZ40 billion ($A38 billion).

The massive effort deployed to restore the city’s infrastructure has created a need for a huge amount of resources. This unprecedented demand has continued to grow, challenging local building companies and construction materials suppliers to step up their production.

Isaac Construction has been a supplier of construction materials to the Christchurch region for many years. Much of the company’s quarry product is consumed in concrete and asphaltic concrete production. Isaac Construction is one of the companies that took on the challenge of meeting this ever-increasing demand, to help rebuild Christchurch. Initially the company achieved additional volume through a lot of hard work, driving its production staff and existing equipment to their limits.

However, it soon became apparent that the need to expand the company’s production facilities was inevitable, to ensure its ability to reliably meet demand.


Established by the Isaacs family in 1957, Isaac Construction’s McLean’s Island Quarry is one of the oldest established quarries in Christchurch.


The quarry converts its raw material feed of incredibly hard, ancient river gravel into coarse natural concrete aggregate, blended sand (natural and Barmac dust), sealing chip for roads and aggregates for asphaltic concrete. Located just 18km from the centre of Christchurch, the quarry is ideally placed to efficiently supply products for the city’s reconstruction work.

Caring for the interests of the community and the environment has long been part of Isaac Construction’s business approach.

The company’s slogan – “combining construction with conservation” – is proudly demonstrated through the work of the Isaac Conservation and Wildlife Trust, which was established by Sir Neil and Lady Diana Isaac in 1977. The trust focuses on three areas: flora, fauna and historic building conservation. In addition to the trust’s conservation of rare plant species, its captive breeding program rears for release a wide variety of New Zealand’s most endangered birds and reptiles. An important source of funding for these visionary conservation projects is profit made in the quarrying business.

Today the trust’s facilities consist of a heritage village, the Isaac Conservation Park, Peacock Springs conservation area and farmland, which are all co-located with the quarry on 1100 hectares at McLean’s Island.


After the 2011 earthquakes, Isaac Construction ramped up production and eventually ran double shifts to meet the increased demand for concrete production and road building materials.

However, the plant’s production capacity and reliability started to become a major issue. This sometimes resulted in the need to buy in products to satisfy supply obligations. Towards the end of 2011, the company’s management team agreed an upgrade was required and boldly decided to treble the quarry’s production capacity from 100 to 300 tonnes per hour.

A tender process was initiated in February 2012 and after months of detailed bid reviews, Isaac Construction awarded an $NZ11 million contract to Metso’s New Zealand distributor MIMICO. The contract included the design, supply, installation and commission of a new plant based on Metso’s crushing and screening equipment, as well as its wear protection system. The plant was designed, fabricated and installed by QMI Engineering, a fully owned subsidiary of MIMICO. Commissioning was undertaken by MIMICO’s in-house service team. The upgrade was completed in three stages. Work on the primary and secondary sections started in early 2013 and was completed in September 2014. The tertiary section was started in November 2014 and was completed by May 2015.


This project represented a significant investment for Isaac Construction, so flexibility around the payment terms was a high priority for the company’s management.


“As part of the project conditions, we offered Isaac Construction a monthly payment arrangement,” MIMICO’s managing director Rex Davies said. “This required careful planning on our side because we needed to synchronise the project’s progress with the payments as best as we could.

“Obviously, there were instances when it wasn’t possible to get the timing right, so financially it would be a bit tough for us for a month or two, as we still needed to continue paying our suppliers on time.

“This was a great result for Isaac, as quite uniquely, the arrangement allowed them to make all of their payments from cash flow. I am quite certain that our payment package was an important factor in the decision to award us the contract.”

Isaac Construction’s maintenance supervisor Stu Cameron said choosing MIMICO as the supplier of the new plant was a good move.

“A big factor was the confidence we had in the working relationship,” he said. “All the key people on the project from QMI Engineering and MIMICO knew our plant and company.

“In particular, [QMI’s] Colin and Scott Welsh had been involved in maintenance and plant improvements here for many years prior to the start of the project.

“Another important factor was the reliability of our existing Metso crushers. In our old plant, we had a Metso HP100 and a HP200. Both machines were close to 20 years old and were still running strong.”

Colin Welsh founded QMI in 1989 and has been personally involved with Isaac Construction since 2000.


“When we first started doing work for Isaac Construction it was just maintenance over their Christmas shutdown period,” he said. “Over the years this grew into doing refurbishments and small upgrades to improve production rates, or to add the capability to produce different products. There is no doubt that our long-term relationship played a big part in us being awarded the contract.

“On our side, we had developed a deep trust for the people at Isaac Construction. This was a significant factor in our risk evaluation of the payment arrangement for the contract.”


The feed stock from McLean’s Island Quarry is infamous for its hardness.

This factor alone made designing an optimal plant complex. Contributing to this complexity was shifting market demand, in terms of both volume and variety of product. This forced Isaac Construction to change the required project specifications.

While changes such as this are understandably unpopular with contractors, MIMICO’s process equipment engineer David McCaffrey was of the opinion that his company’s ability to quickly interpret changes, adapt process models and select suitable equipment helped it win the project.

“BRUNO is Metso’s easy to use software tool for planning and simulating the crushing process,” McCaffrey said. “It helps us to quickly explore various machine combinations for different applications. We use it extensively. On this project, I created many alternative models in BRUNO before proposing our overall design.

“When Isaac advised us about expected increases in sales production volumes for various products, I quickly made changes to input and output parameters and within minutes was able to assess the performance of the various models I had previously built. This allowed me to quickly understand what changes we needed to make to our offer.

“We also excelled in addressing the uncertainty of Isaac’s feed stock hardness, as we have our own laboratory, which conducted extensive crush tests for us.


“The combination of using accurate crushability data and presenting BRUNO process models gave the management at Isaac Construction a high degree of confidence in the reliability of our design.”


In discussing the project outcome, Cameron said Isaac Construction was extremely impressed with the overall plant.

“Overall, things went really well,” he said. “It is hard to try to single out anything that stands out. I would say, though, that the advanced safety levels in the new plant have really impressed me.

“Based on what I have seen, I think it has possibly worked out cheaper to install new plant than to try to get the existing plant up to the same safety standards required to comply with New Zealand’s latest safety rules.”

Isaac Construction’s industries manager Mike Higgins is responsible for the running of all the company’s production facilities.

He said the high level of safety provided by the new plant had ignited a wave of safety awareness.

“Suddenly we all started looking at things differently and have become very proactive in increasing our safety performance,” Higgins said.

“In fact, the Quarry Inspectorate has recently asked me to present at their conference on the safety modifications that we have made to the nip point of our tail drums.


“Sometimes it is just simple things like fitting handrails or fixed ladder access that can make a big difference to the safety of our personnel.”

The project delivered numerous optimisations, cost savings and process efficiencies for Isaac Construction.

According to MIMICO’s managing director Rex Davies, an example of how the new plant reduced costs was the elimination of the load and carry aspect of the process.

“Previously the plant consisted of three sections, and so at any one time there would be four or five wheel loaders moving product between sections for the next stage of processing, doing up to 120km a day,” he said.

“Not only did this mean high fuel and maintenance costs, but it was also a big capital outlay. The new plant has a network of conveyors, removing this requirement completely.

“I am very satisfied with the way that our team has performed and the outcomes we have delivered for Isaac Construction.

“Our collaboration throughout the project has strengthened our relationships. I’m pleased to say that through the process we have established a good, loyal and long-term customer.”

For Higgins, the flexibility of the new plant is what impresses him most.

“We have a fairly unique situation in this region,” he said. “At times it’s a real challenge to produce what the market needs from the feed gravel we have available to us. The gravel is very hard, and this makes it expensive to produce large volumes of fine-crushed material.

“Thanks to this project, we have been able to optimise our costs far better than other quarries. Lower costs and the ability of the new plant to easily change the product specification have made us very competitive in meeting market demands.

“It is a credit to David McCaffrey and the MIMICO team that they were able to build in additional flexibility to accommodate a wide variety of product specifications – a variety that even increased during the course of the project.”

Colin Welsh talks fondly of his involvement in the project and QMI Engineering’s work at McLean’s Island Quarry.

“It is 15 years of history for me,” Welsh said. “If I look back, there were three different plants each dedicated to making a specific product.

“Today I see a single plant that takes its feedstock on the one end and produces multiple products in multiple stockpiles. Thanks to the high degree of automation and advanced SCADA user interface, deciding and changing what product gets made and where it is stockpiled is a matter of keystrokes in the control room rather than hours of work out in the field.

“What this project has delivered to our long term customer is certainly a distinction in my career.”

Source: Metso

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