Value Added Through Washing In County Tipperary

• 
• 23rd October 2008
• Quarrying
 

A new CDE washing plant installed at Seamus Ryan Sand & Gravel in County Tipperary has increased the value of the final products by 50% since installation.

The quarry is located outside Toomyvara - a small village on the N7 between Roscrea and Nenagh - and has been in operation since 1999. Up until the recent installation of the CDE plant, the company was dry screening all 25mm down material at the site. The decision to introduce the washing plant came after several discussions with CDE about the added value that a CDE washing plant could bring.

"After sticking with the dry screening for some considerable time, we were just not happy with the final price we were able to get for the products we were selling" explains Seamus. "We were just not achieving clean products and we were not able to remove all the excess fines. Both of these factors combined were reducing the sell price of our products significantly."

CDE's considerable experience working with difficult materials and successfully adding value was key to their selection as the supplier for Seamus Ryan's new washing plant. The product output from this site was being sold by the company for further processing in order to maximise its commercial value. This was margin that Seamus Ryan was missing out on.

"When I looked in detail at the additional margin I could get for the final products by installing a more effective processing system, it dealt with any concerns that I had about the size of the initial capital investment" explains Seamus. "Given the capacity of the plant that we have installed, the pay back period for the new CDE plant makes the investment very worthwhile."

Project Outline

The plant installed by CDE has a capacity of 300 tons per hour and processes -25mm material. The equipment supplied by CDE includes a 55ton feed hopper with combined 25m inclined conveyor. This conveyor feeds a large triple deck rinsing screen from CDE's ProGrade range. The product output from this screen is 3 sizes of chips: 6-10mm, 10-20mm and +20mm - which are discharged into concrete bays. The -6mm material is sent to one of CDE's EvoWash dual sand plants and produces concrete sand and building sand. The sand plant removes all the -63 micron material and this is sent to the AquaCycle Thickener along with the waste water. The sludge from the thickener tank is then pumped to ponds, while the clean water is recycled back to the washing plant, significantly reducing the requirement for fresh water to feed the system.

Transfer Point Technology

The washing plant begins with one of CDE's hopper and conveyor combinations. This particular unit as a 55 ton hopper with a 25m inclined feed conveyor to feed the screen. CDE developed this particular product as part of their continuing focus on ‘transfer point technology' as explained by Design Manager, Brian McCullough.

"Our focus on all the transfer points between the individual pieces of equipment in any installation is driven by the aim to ensure the plant runs as efficiently as possible. By reducing spillage at key points we are ensuring that the customer gets the maximum possible product at the end of the process, thus guaranteeing maximum revenues."

The washing process

From this conveyor, the -25mm feed material is transferred to the first stage of the washing process. This stage involves a large triple deck rinsing screen from CDE's ProGrade range. This R3M140 (7m x 2m) screen washes and sizes the products into 20mm, 10mm and 6mm chips, which are discharged into concrete bays. The -6mm material is then sent to a CDE EvoWash sand plant.

The sand washing phase of Seamus Ryan's plant includes a dual sands plant, producing both concrete sand and building sand. The A series plant, has a split screen, dual cyclones and includes a 10/8 Warman pump. This plant accurately removes the -63 micron material from the sand, leaving high specification products for Seamus Ryan to sell to his local market.

"The type of technologies that combine to make up our EvoWash sand plant range ensure that it is the best performing sand washing technology available on the market" says Enda Ivanoff, CDE's Sales Director. "We use high quality components throughout - Warman pumps, polyurethane screen decks, hydrocyclone technology. We know our customers' requirement is the maximum amount of product on the ground and that is what our plants are set up to deliver"

Ensuring high performance

Expanding on this point, Enda highlights the fact that all CDE sand plants, and indeed their full equipment range, is cutomised to the individual requirements of the customer. Each plant is built with a proper analysis of the feed material having been undertaken at CDE's laboratory in Cookstown, County Tyrone. This enables the technical team to build the plant to cope with the individual characteristics of the feed.

"We know that the feed from any 2 sites is not the same, so it does not make sense to offer off the shelf products to deal with entirely different situations. By building each plant to the individual customers' requirements we can ensure they have the maximum quantity of high specification products available to sell. Our sand plant range has been proven in numerous worldwide installations to remove the -63 micron material more effectively than any other option currently available" states Enda.

Reducing environmental impact

The -63 micron material and waste water from the washing process are sent from the EvoWash sand plant to the water treatment phase of the plant. This involves an AquaCycle T08 high rate thickener, which has a diameter of 8m and can deal with 400m3 of water per hour. This water treatment stage also includes a fully automated polyelectrolyte dosing station.

As the waste material enters the tank it is mixed with a small amount of flocculent. This forces all the silts and clays to form a thick sludge that settles to the bottom of the AquaCycle tank. A set of rakes are fitted to the bottom of the tank and these gently rotate to prevent it from setting and also to move it towards the discharge point at the bottom of the tank. The rakes also send information concerning the amount of resistance they are encountering back to the PLC control panel, which automatically starts and stops the main sludge pump as required. The thickened sludge is then pumped to setting ponds on this particular site.

Meanwhile, the clean water that has been separated from the sludge overflows the top of the thickener tank and is stored in a recycled water tank and then recycled back to the washing plant. The water treatment stage of this plant significantly reduces the environmental impact of the operation by significantly reducing the amount of fresh water required to feed the system.

Full Project Management

CDE were responsible for the delivery of every stage of this new washing plant for Seamus Ryan Sand & Gravel. This began with the design and specification of the equipment in the first instance, to the manufacture of all the equipment provided. In addition to this CDE were also responsible for the installation and commissioning of the plant.

"The continuity of contact was a major advantage" comments Seamus Ryan. "Throughout the whole process it was CDE who were managing each stage. This made it very easy to understand exactly what stage we were at and made sure that all those involved on the project had a full understanding of what had gone before, and what was to happen next."

In addition to this, Seamus Ryan has also agreed an ongoing service and maintenance package for the plant. This will involve monthly plant inspections for the first 3 months followed by bi-monthly inspections from one of CDE's service engineers. This is one of the options offered by CDE as part of their ‘ServiceMax' package as explained by After Sales & Service Manager, Raymond Cooke.

"Our experience in running numerous washing plants allows us to ensure that the plant continues to perform at an optimum level, thus maintaining the required production levels in relation to the volume of material coming off the plant and the specification of this material. The packages we offer include recommended spares lists and preventative maintenance contracts which aim to ensure the plant is running for the maximum time possible. These elements of our service allow us to significantly reduce plant down time and have been proven on many installations."

Continuous Improvement

Since commissioning of this CDE washing plant Seamus Ryan has seen a 50% increase in the value of the products he has available to sell. This is a result of the higher specification of the material being produced as a result of CDE's washing technologies being introduced to the site.

All 5 products being produced by Seamus Ryan Sand & Gravel are of a superior quality to those products that were the result of the previous dry screening operation. The use of high specification components on all of CDE's equipment is the first stage of this process but this is supported by a continuing focus on innovation and improvement of the current systems.

"As a company we have built our reputation on the delivery of new technologies to the market and this will continue to be the case" explains Design Manager, Brian McCullough. "We have a detailed continuous improvement program in place which ensures we can continue to get better and more efficient at everything we do."

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