Alan Titchall revisits Websters Hydrated Lime in the Hawke’s Bay as it opens more resource with new consents that guarantee the operation for another 70 years.
With WW2 over a young engineer called Bruce Webster returned from the UK and Italy. Bruce, and his brother Maurice (an accountant), were looking for work.
Bruce wrote to their uncle Nicol Webster who was chief executive of engineering company Cory-Wright & Salmon in Wellington.
Nicol wrote back and said there was a defunct lime operation near Havelock North that used to make hydrated lime for use in the building industry as mortar.
The three of them put in a tender for the site, which won, and then went to the library to do some hasty research, because none of them had a clue about limestone extraction, or the lime burning process. The date was April 1946 – exactly 71 years ago.
Within a few months, the Websters had partly restored the operation, which allowed them to begin supplying local freezing works with lime for fellmongery (stripping wool off sheep pelts) and tanning.
As they redeveloped the site, the Webster brothers built almost everything themselves, from modifying a recycled army truck, replacing the old hand-pushed rail carts used for loading kilns, to making an automatic bagger. Their innovations included swapping jute sacks for the first paper sacks used in his country. These had to be imported from India as NZ Forest Products (ex Carter Holt Harvey) was not making them at this stage. They also experimented – building their first test kiln in the late l950s to improve burning of small stone.
By the early 1960s the lime resource had thinned out and, in 1963, they bought eight hectares of hilly, westerly facing farmland just off Middle Road on the eastern side of Havelock North village.
Initially, extracted limestone was carted to the old site for burning. In 1968 they produced their first burnt lime at the Middle Road quarry using a rotary kiln. This burnt lime was then carted to the old site for hydrating.
Bruce’s son, Robert Webster, joined the company the next year in 1969 on a temporary basis as he was between jobs. He caught the quarry bug and stayed on. By 1975 the old site had been sold and Middle Road quarry was operating on its own.
Robert had a hand in building some of the equipment still in use today, including the fluid bed kiln that began working in 1978.
He and his father then bought out the other shareholders in 1986 and a new era of burnt lime began.
One of only two
These days Websters Hydrated Lime, with a resource of about 10 million tonnes of high-quality limestone, is the only burnt lime operation in a region sitting on large hills of the material.
The company is also one of just two companies in the country specialising in the production of value-added limestone-based products such as burnt and hydrated limes, ag lime, fine ground limestone, lime and limestone road mixes and construction stone.
The other company is McDonald’s and Taylor’s Lime (Holcim), which was bought two years ago by Canadian-based company, Graymont. They run plants in Otorohanga and Dunback (South Island).
Lime deposits vary greatly around the country, in terms of hardness and quality and the country’s two burnt lime producers treat the product in different ways. The Webster lime is a soft limestone, less dense and is valued for its free-flowing qualities in the agricultural industry. The Webster lime is also softer burnt – around 950 degrees Celsius. Graymount’s lime at Otorohanga and Dunback is a hard limestone and is burnt around 1100- 1200 degrees.
My visit to the quarry over the past summer was hosted by managing director Robert Webster and we talked a lot about the legacy of his father Bruce, a founder member of the IOQ, and preparations for Robert’s own two sons to take over the operation. Which means this quarry remains a very family business.
Robert took over from his father in 1995, and was joined by son Nick in 2005, who is trained in mechanical engineering (specifically for the lime industry). Robert’s younger son Matt joined the company in 2010. Matt trained in marketing and sales, has a seat on the IOQ board, and has a keen interest in industry recruitment and training.
“I suppose I am the managing director, Nick is operations manager, and Matt is the sales manager, but it depends on what day of the week it is,” says Robert.
“We can all do each other’s jobs and operate the plants and machines.
“I will be slowly reducing my involvement allowing more time for travel, beach and motor sport.”
From the very top of the quarry, where the grass reaches up to your knees, the view west across Middle Road and over the valley is awesome. The surrounding hills are carpeted with long grass the summer has bleached golden brown. The hills are also treeless, a natural state that even Captain Cook mentioned. In stark contrast, the valley in the distance is lime green.
“It used to be a vast swamp,” says Robert. “Then the farmers drained it and put artesian bores down so they can irrigate for a large range of crops.”
On the other side of the valley is a set of hills dotted with ‘lifestyle’ homes. Typical of townies moving into the countryside and then complaining of local industries, many of them objected to Websters Lime’s new consent, even though they are five kilometres away from the quarry.
“Our original consents were granted in 1964 and they were very generous,” says Robert.
“To expand our eastern boundaries we traded some of those consents for new ones, which are workable.”
The farm on the eastern boundary was granted by council an ‘as of right, non-notified consent’ for up to 48 new house sites. Robert says at least five of those homes would have been built within 20 metres of his quarry. Websters challenged the consent and got council to have an open consent hearing.
“We were successful in removing all house sites from our boundary and having a notice of the quarry placed on all the sites’ LIM reports.”
They haven’t sold any yet, he adds pointedly.
As the prevailing wind is westerly, often very strong, and the lime dust line fine, one would want to do due diligence before building up at these heights.
On top of the lime is a six-metre thick layer of overburden mostly made up of ash from the Taupo eruption and others thousands of years ago.
Under a top layer of lower-quality lime is the good stuff – made up of soft lime with some hard (around 10 percent) bands. A 50-tonne excavator is used to dig all materials and even make the haul roads. Three Volvo loaders (an L20 and two L70s), and two off-road, old Komatsu dump trucks, make up the quarry fleet.
A comprehensive plant features undercover storage for all products and an onsite laboratory for quality control – verified by independent labs.
In total the quarry produces, from a 150-metre deep seam of lime, between 80,000 and 100,000 tonnes of product a year. Most tonnage is agricultural lime, around 60,000 tonnes a year, and it has a reputation among top dressing pilots and spreader trucks for its free-flowing qualities (produced through a process the Websters keep to themselves).
The lower grade limestone is crushed and supplied to the local horticultural and dairy industries – for orchard tracks, driveways, and farm races.
The quality lime is crushed in the primary plant with a single rotor impactor in one-pass, producing 110 tonnes an hour of 100ml product.
“A good little plant and easy to maintain,” says Robert.
A fine-grinding plant reduces the limestone to grains of less than 100 microns for the fertiliser and dairy industries, and is even used as a filler in glues and paint.
Limestone is ‘burnt’ to rid it of its carbon dioxide (CO2); then water is added to produce an alkaline product (hydrated lime) used in a variety of industries, including water quality treatment.
When lime is dried at high temperatures it loses its CO2 and becomes calcium oxide. Websters’ kilns run 24 hours a day, seven days a week as needed, to maximise the value of the quarry’s soft, and finer-grained limestone.
The rotary kiln and plant has evolved over 30 years from a custom design and is very efficient, especially after a pre-heater was added last year that uses exhaust gas to pre-heat the limestone.
The heat source is pulverised slack coal, around 22 tonnes a day when both kilns are running. The coal crusher/pulveriser was bought from the Silver Fern Farms freezing works in Hastings when it converted to gas.
The coal dust heats the kiln to 950 degrees Celsius to produce burnt lime (CaO, calcium oxide) for production of hydrated lime and the roading industry. When you add water to calcium oxide a chemical and physical reaction turns it to a fine white alkaline powder called calcium hydroxide (Ca(OH)2, hydrated lime).
The process employs up to 15 people at the quarry/plant with the product being sold to councils (water and effluent treatment plants); tanneries and fellmongers for the leather wool industry ; soil stabilisation projects; effluent treatment plants; and is also used in the manufacture of fruit sprays, gelatine, mortars and plasters.
Burnt lime is sold in one tonne bulk bags, hydrated lime in 25kg bags, 600kg bulk bags and bulk via Websters’ own tankers.
Some time ago the Websters designed a bagging press after a staff member hurt his back stacking 25 kilogram bags of hydrated lime.
Set to a convenient stacking height, the press sinks as more bags are loaded onto the pallet.
When the pallet is fully loaded, hydraulics raise and compress the stack against the lid, squeezing excess air out of the bags and making them easier to strap.
This press won Robert Webster, who is a long-standing member of the IOQ and holds an A-Grade quarry certificate, the institute’s Niederer Machinery Award in 2000.
The carbon fiasco
In a ‘carbon’ (think carbon dioxide) obsessed world using a process that gives off CO2 comes with penalties, much like the old church ‘indulgences’ one could pay to reduce the amount of punishment one had to undergo for ‘sins’.
And the theory of ‘manmade’ climate change has become more of a religion than science, as a growing number of scientists agree that long-term climate change is a ‘natural’ phenomenon.
Meantime, the Websters will soon be paying $25 per tonne of CO2 for burning coal and another penalty for releasing CO2 into the atmosphere through burning lime (some 45 percent of limestone is made up of CO2).
This is very ironic because lime is a well-known and useful absorber of C02, and this is one of the functions of hydrated lime.
Hydrated lime is widely used in fruitgrowers’ climate-controlled stores to maintain crispness in apples, as well as by water treatment plants to absorb unwanted CO2 from water supplies. Burnt lime/hydrated lime over its life will reabsorb the CO2 released when it was produced. It is also CO2 that keeps Hawke’s Bay looking so green and productive.
This information has fallen on deaf ears in Wellington as various industries that are in a similar situation (such as concrete) are turned away for being too hard to manage under our almost comical ‘carbon’ credit/costs regulations.
Another lime product produced at Websters Hydrated Lime is an equal combination of crushed lime and superphosphate mixed with water (10 percent) called dicalcic.
It is made for Ravensdown, which supplies the superphosphate, and is used in aerial top dressing and truck spreading.
Made in 1000 tonne batches, the mixture (around 10,000 tonnes a year) is left to ‘cure’ over 30 days, with the lime making the superphosphate ‘softer’.
Ravensdown trucks, proudly ‘blinged’ up, pick up the mixture from the quarry and transport it to a plant in Napier.
In the hands of the next generation
Plans are for Nick and Matt to take over the operation and Robert to reduce his practical involvement after almost five decades of work.
“Nick and Matt complement each other,” says Robert.
“As kids, they used to fight like hell; now they get on and work together bloody well.
“And the older they get the more they get on, both in the quarry operation and outside sharing interests in fishing and hunting.”
Robert points to a raised area to one side of the quarry entrance and talks about future extraction and processing plant.
Plus, there’s an option on 200 hectares of lime-laden farmland on the boundary.
So, plenty of opportunity for even the next generation as Nick and Matt’s own children grow up in the quarry/lime culture.