Rock to Road

Features Aggregates Technology
Quarry builds on quality reputation

A new screen has boosted plant efficiency at a versatile quarry operation.


February 1, 2010
By Andy Bateman


Topics

Located on the Niagara Escarpment some 25 km west of Niagara Falls On., the limestone quarry operation of Vineland Quarries & Crushed Stone Limited enjoys a reputation for supplying quality aggregates to the local construction market.

Located on the Niagara Escarpment some 25 km west of Niagara Falls On.,
the limestone quarry operation of Vineland Quarries & Crushed Stone
Limited enjoys a reputation for supplying quality aggregates to the
local construction market.

Walker-(3)
 The new Tycan HSG T- Class S inclined screen at Vineland is delivering a number of process improvements including increased productivity, more screen media choices, improved product cleanliness and reduced wash water volumes.


Quarry superintendent Evan Bartfai explains that the Walker Industries
Group operation produces a full range of aggregates from the uniform
dolomitic limestone deposit, including washed coarse and fine
aggregates for concrete, asphalt and landfill applications as well as
granular base materials; “The multi-stage production process at
Vineland has been designed to meet customers’ demands for clean cubical
products that consistently meet gradation specifications. Cubical
product shape is the result of three crushing stages, while tight
product gradation is achieved by a multi-stage screening, washing and
product blending process. In addition, we have recently installed a new
inclined screen to increase the output of washed coarse product
fractions while reducing the demand for fresh wash water.”

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Walker-(0) 
A Caterpillar 988H wheel loader and Hitachi EH700 haul truck on material handling duty at the Vineland quarry.
 
Walker-(2)  
Size fractions off these two Terex Simplicity 7x 20 triple deck screens are directed to
separate downstream screens for tighter finished production gradation control. 
 
Walker-(1)  
This Metso HP 400 SX cone crusher is one of a matched pair in the secondary crushing position at Vineland.


 

Bartfai notes that the Vineland deposit is normally worked in two
faces, each about 7.5m high. The upper bench is suitable for asphalt
and granular products and the lower bench, although suitable for all
products, is used primarily for concrete applications. In normal
production, a Caterpillar 988H face machine loads three primary haul
trucks including two Hitachi Euclid EH700’s and a Caterpillar 769. The
trucks discharge into a primary dump hopper from which a Simplicity
feeder regulates the flow of shot rock to a Cedarapids 4248 primary jaw
crusher. Jaw product, 165mm minus crusher run, is directed to a
Telsmith two deck screen where material already sized at 25 mm and
smaller is separated as Granular A base material and material larger
than 25 mm goes forward to a surge pile.

Beneath the surge pile, a Jeffrey feeder in the roof of a reclaim
tunnel feeds material to a 100 tonnes capacity surge bin where a
Syntron feeder maintains a steady flow of material to an enclosed
Symons 1.68 m cone crusher in the secondary position. The cone’s
discharge, typically sized at 75mm to 100 mm minus, is then separated
on a Tyler 6 by 16 double deck screen fitted with 25 mm screen cloths
on the upper deck and mixed 19 mm and 16 mm screen cloths on the lower
deck. Material passing the bottom deck is separated and stockpiled as
Granular M base, with larger sizes retained on both the lower and upper
decks directed to the plant’s tertiary crushing stage. Here, further
reduction is completed by a pair of Metso HP 400 SX cone crushers, with
crusher product conveyed to a pair of Terex Simplicity 7x 20 triple
deck screens fitted with mixed 25 mm and 23.8 mm, 13 mm Flex-Mat and
mixed 4.8 mm and 3.2 mm media on their top, middle and bottom decks
respectively.

Oversize retained on the top decks of the Simplicity screens is
returned to the HP 400 cone crushers for further crushing while
material smaller than 4.8 mm passing their bottom decks is directed to
an Eagle Iron Works (EIW) nine station sand classifier. The treatment
of intermediate fractions off the Simplicity screens is unusual in that
material retained on their second decks (minus 25 mm plus 13 mm) is
directed to a new Tyler 7 by 20 screen, whereas material retained on
their bottom decks (minus 13 mm plus 4.8 mm) is directed to a KPI-JCI 7
by 20 screen. Bartfai explains that this arrangement allows narrower
size fractions (cuts) to be separated, with the Tyler screen separating
larger size coarse fractions and the KPI-JCI screen separating smaller
size coarse fractions. These narrower cuts allow tighter production
control when the fractions are later blended back together to meet
final product gradations. 

The new Tycan HSG T- Class S 180C 7×20 3D rinsing screen from Tyler is
fitted with 16 mm, 13 mm and 3.2 mm screen cloths on its top, middle
and bottom decks. Material retained on the top deck is directed to a 19
mm storage bin while material retained on the middle and bottom decks
is conveyed to a 13 mm storage bin and minus 3.2 mm is directed to the
EIW classifier via a feed hopper.

For many operators, this additional screening would be the final
processing stage. Not so at Vineland, where the washed coarse fractions
are blended in the required ratios from the separate storage bins
downstream of the screens and only then stockpiled as finished product.

Bartfai adds that the inclined Tyler screen replaces a Tyler L class
horizontal 7 by 20 unit in the same position, with the switch
delivering a number of process improvements. The inclined screen is
more productive than the horizontal unit and also provides more screen
media choices. Reduced water consumption was an additional objective,
as the previous screen had a wet feed box requiring large volumes of
fresh water. The new screen’s feed box is dry, with all material
rinsing completed by multiple spray bars on each screen deck. Bartfai
is pleased with the cleanliness of product from the new screen, with
laboratory test results to date showing minimal piggy back fines even
though wash water volumes have been reduced. The screen went into
operation fitted with square wire cloth and Tyler’s Cobra Vibe PQ
media. Urethane media has not been tried at this point but can be
readily fitted using the screen’s standardised screening media support
system. This particular unit is fitted with an optional wear and tear
protection system known as Snap Guard, designed to protect cross beams
from being struck by material passing through the media.

Benefits listed by Tyler for the new T-Class screens also include
modular construction, rigid frame design and easy modifications to the
drive setting. This is reportedly the first North American application
for the HSG T – Class screen, for a global total of some fifteen units
currently in service worldwide. These screens are designed to provide
separation in the 300 mm to 3 mm particle size range and are usually
installed at an angle of 15 to 25 degrees with operating speeds of 750
to 1050 RPM. The two bearing, circle throw screens are available with
one, two or three screen decks in widths from 0.92 m to 2.44 m and
lengths up to 7.32 m. Available media include perforated plate, rubber
screen sections, rubber clad plates, end-tensioned harp-type screen
sections and several modular urethane deckings. The PQ style screen,
one of four Cobra Vibe designs, consists of two horizontally crimped
warp wires designed to create a square opening and screening accuracy
close to a regular square opening. At the same time, the design allows
all warp wires to vibrate independently from each other to provide
excellent self-cleaning action, says Tyler.


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