| MAGAZINE | ||||
|---|---|---|---|---|
|
| MARKETPLACE | |||
|---|---|---|---|
|
|
|
| COMMUNITY | |||
|---|---|---|---|
|
| RESOURCES | |||||
|---|---|---|---|---|---|
|
|
|
 |
Quarry builds on quality reputation A new screen has boosted plant efficiency at a versatile quarry operation. |
| Written by Andy Bateman | |
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.
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.”
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 7x20 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. |
|||||||||||||||
.jpg "Walker-(3)")
.jpg "Walker-(0)")
.jpg "Walker-(2)")
.jpg "Walker-(1)")
|
|
| Related Articles |
|---|
|
Canada’s Top 10 Aggregate Operations by Andy Bateman | 06/10/2010 State of the industry by Andy Bateman | 02/22/2010 New wash plant doubles output by Andy Bateman | 02/22/2010 Kelso Quarry Park by Sarah Lowe BSc MSC & Sherry Yundt BA MA FIQ | 02/01/2010 Focus on Portable Generator Sets by Aggregates | 01/12/2010 |
