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Singleton Birch are lime producers witha history that dates back to 1815 whenthe company was first established inManchester.Around 1830 William

Singleton Birch joined the company and overthe following years developed a mineralmerchanting business serving the Manchesterarea; in 1875 he became the founder ofW. Singleton Birch & Sons Ltd.

Around 1850, after the railway line wasextended eastwards from Manchester viaSheffield and through to Grimsby, recordsshow that William Singleton Birch was leasingland from the Earl of Yarborough at Chalk Hill,Melton Ross, for the purpose of quarrying andthe manufacture of whiting. By the time hedecided to pass on the ownership of thecompany to his two sons he had built up aconsiderable business, mainly in Lancashire,where he had developed warehousing and

distribution centres based on rail and canaltransportation.

The younger son,Thomas Henry Birch,carried on in charge of the company asmajority shareholder until his death in 1919. Itwas Thomas Henry’s wish that the grandson ofWilliam Singleton Birch, Lionel Walker BirchMartin, should inherit his 95% shareholding.Although Lionel Martin was a director of thecompany, most of his time was spent on hisfirst love, fast cars, and he gave his name tothe legendary Aston Martin car. Hisautobiography references his quarryinginterests in Lincolnshire helping to fund whatstarted off as a hobby. He died in 1945 and hismajority shareholding was passed to hissecond wife, Katherine Martin. Katherine diedin 1958, leaving most of her shares in trust forthe benefit of three charities — NSPCC,RSPCA and Barnados.This trust is still the �

Singleton Birch InvestFor The FutureSingleton Birch Ltd, based at Melton Ross in North Lincolnshire, are the UK’s largest independent lime producers.The company supply quick lime, hydrated lime and chalk products to a range of industries including iron andsteel, construction, chemical and water treatment.They have recently invested over £3 million in a state-of-the-artcrushing and screening plant for the production of limestone fines, predominantly for the large integrated steel-works owned by Corus in Scunthorpe. Richard Stansfield, production and landfill manager, reports.

Singleton Birch’s new limestone fines plant with restored land in the foreground

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majority shareholder in the company today.Throughout the 1960s steel-making

practices changed and shaft limekilns wereintroduced at Melton Ross to produce burntlime products to replace the use of raw stoneas a flux in the steel furnaces at Scunthorpe.The company’s first slaking plant wascommissioned in 1965 to produce a high-calcium hydrated-lime powder.The shaft kilnswere partially replaced in the early 1970s withtwo 300 tonnes/day gas-fired rotating hearth(calcimatic) kilns to meet the high quality andincreased volumes demanded by thesteelworks.

As a result of the fuel crisis in the late1970s Singleton Birch constructed the first oftheir four 300 tonnes/day Maerz parallel-flowregenerative kilns.This type of kiln produces agood quality lime product using significantlyless fuel.The four Maerz kilns at Melton Rosswere commissioned in 1981, 1984, 1986 and1996.

Significant capital investment has been madein the company’s processing capability atMelton Ross Quarries. Downstream from thekilns equipment has been installed tomanufacture a wide range of lime products tomeet customer requirements.There is alimited amount of associated storage availablefor each product and therefore sales/production planning has become a keyrequirement, particularly when faced withfluctuating customer demand for burnt lime.

In the late 1990s the company realized anopportunity to continue the restoration of thequarry at Melton Ross through the landfillingof non-hazardous filter cake residues fromtitanium dioxide manufacturers located on theHumber Bank. Investment was made todevelop a fully engineered landfill site tocontain these filter cakes.

Today, the principal activity of the company

is quarrying chalk with the associatedmanufacture, sale and distribution of lime andchalk products and landfill operations.Thecompany operate three chalk quarries atMelton Ross, Mansgate and South Thoresby.

STONE PRODUCTIONThe quarry at Melton Ross extracts over1.6 million tonnes of chalk a year.The depositforms part of the Northern Province UpperCretaceous sequence, which is a hard,massively bedded chalk containing a smallpercentage of flint nodules.

Following overburden removal, 108mmblastholes are drilled using a Hausherr 55HDhydraulic drill rig.The explosive columnconsists of a single 0.5kg primer and twodetonators at the bottom of the hole with therest of the column charged with ANFO from amini-mixer mounted on the back of anagricultural tractor.

Blasting normally occurs on a daily basiswith a three- or four-hole blast yielding4,000–5,000 tonnes of chalk.With saturationmoisture content approaching 14% it isessential that the chalk is kept as dry aspossible to avoid handling problems in theplant, hence the frequency of blasting.

The fragmented rock pile is then transferredto MMD semi-mobile primary and secondarycrushing units using two 50-tonne wheelloaders, either Cat 988s or Volvo 330s.The topbed consists of a MMD 750 primary and aMMD 500 secondary, the bottom bed a 1000and a 625, respectively.

The primary and secondary crushers reducethe product size to –150mm.This is conveyedat an average rate of 400 tonnes/h to ascalpings plant where two Hunt West screensseparate out the –25mm fraction and the–50mm+25mm fraction.This material isconveyed to the new limestone fines plant.

The new limestone fines plantunder construction at MeltonRoss Quarry

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The –150+50mm fraction is transferred to aconveyor and transported, via a tunnel, to themain processing plant situated on the otherside of a public road. Here the material isfurther sized into 50–75mm, 75–100mm and100–150mm fractions ready for burning in thelimekilns.

NEW LIMESTONE FINESPLANTThe original limestone fines plant consisted ofcrushers and screens designed to produce a–3.35mm product that is used as a flux byCorus in their iron-making process. SingletonBirch have supplied the Scunthorpe steel-works with limestone fines for a number ofyears.The fines produced were from a plantbased on old-technology hammer mills andconventional multi-deck sizers. Owing to the2% flint content of the chalk and high moisturecontent, this was an arduous crushing job andwear-rate costs were high and efficiency low.Because of the moisture content of the chalkdeck heating on the sizers was needed toprevent blinding of the meshes, which alsorequired high maintenance.

It was decided in 2000 that with increasingdemand from the customer a new plant wouldbe necessary for the future that would allowincreased production from a plant with lessequipment, reduced maintenance costs,reduced power requirements, consistentgrading and state-of-the-art safety andenvironmental features.

With this difficult brief the engineering andproduction team set about a complete reviewof what the latest developments in crushing,screening and feeding and general plant designcould offer in the new millennium.Tests were

carried out in the UK and other parts of theworld before a decision was made toincorporate two REMco Star 500 vertical-shaftimpactors at the heart of the new plant,working in tandem with screens and feedersmade by Rhewum of Germany. Nottingham-based Conveyor Systems Ltd were selected tobuild the plant.

Feed materialThe plant is fed with the two sizes of materialfrom the quarry scalpings plant.The –25mmchalk is conveyed to a screen where the–3.35mm is separated out on to the productbelt and conveyed straight to the store, whilethe oversize is conveyed to the mill feedhoppers.The –50mm+25mm material is feddirectly into the mill feed hoppers and fromhere the –50mm+3.35mm chalk is fed, viaSkako vibratory feeders, into the two REMcocrushers, the feed rate being controlled by themill’s motor current.The crushed material isthen conveyed to two more screens, theoversize being recirculated to the mills and theundersize conveyed to storage.The materialremains in a closed loop until all passes–3.35mm.

CrushingGiven the large differences between the chalkand the flint nodules, and the high moisturecontent of the chalk, REMco engineers, fromtheir experience of making sand,recommended two Sandmax 500HP anvilmachines with hydraulically lifted swing tops,each with the capacity to produce up to150 tonnes/h of –3.35mm products when fedwith an overall 50mm x 4mm feed in a closedcircuit with the Rhewum screens.These twomachines replace and are expected to �

Flow diagram showing thelayout of the new limestonefines plant

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produce more product than the fourhorizontal-shaft hammer mills previously used.

The cost of each of the REMco crushers hasworked out similar to each of the old type ofhorizontal crushers, although only two arerequired to replace four machines. On thisbasis there has been a direct capital cost savingof 50% with further cost savings being achievedon the capital cost of the downstreamstructures, screens and conveyors.

On the old machines complete hammerchanges were required on a weekly basis,whereas similar work is only required everysixth week on each REMco crusher, savingconsiderable labour and downtime.The cost of

wear parts per tonne of product with theREMco units is proving to be less than onethird of that of the old machines, while powerconsumption has been reduced byapproximately 15%.

ScreeningThe main criterion when choosing thescreening equipment was that the screensneeded to consistently produce a –3.35mmproduct even when the material was moistand sticky. Rhewum (GB) Ltd carried outextensive on-site trials with a small WA-typescreen and proved that, even with a moisturecontent of up 11%, the limestone could be

The crusher house underconstruction; the two REMcocrushers can be seen inposition

Two REMco Star 500 vertical-shaft impact crushers werechosen following extensivetests

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screened efficiently and without any blinding.Three Rhewum WAU 390 x 360/1 screens

where installed, each handling 290 tonnes/h ona 3,900mm wide x 3,600mm long deck inclinedat 38° and fitted with a 4mm aperture squaremesh.To ensure an even spread of materialover the screens, a SVWAU 3900 vibratingfeeder supplies each unit.The screens arevirtually maintenance free and only require2.4kW of power per unit.The outer part ofthe screens and feeders is vibration free so allchute work is flange-bolted to give a dust-tightoperating environment.

Storage and loadingThe limestone fines product is delivered intothe storage shed via a tripper conveyor in the

roof of the building. Ultrasonic level probesare used to indicate when the fines heapreduces the required level and the tripperthen automatically moves to its next position.The storage shed holds approximately 7,000tonnes of product.

Lorries enter the building via a separateentrance where the floor of the building isapproximately 2m lower than the main storagearea.A Cat 972G wheel loader feeds theproduct into the lorries over a small wall, thuskeeping the two vehicles apart.The heightdifference also allows the wheel loader driverbetter visibility into the back of the lorry.

The new plant was officially opened on4 June 2004 by Corus’ chief operatingofficer. �

The three RhewumWAUscreens

The limestone fines storagebuilding holds around 7,000tonnes of product