AUTOMATED MOBILE BATCHING PLANT

 

The equipment utilized by ACT is second to none in the grouting industry. As a result of the specialized nature of our business, we routinely innovate and customize our equipment to facilitate our needs, as well as the needs of our customers. We have a complete line of computer monitoring, grouting batching, and drilling equipment to suit almost any site conditions we encounter. Some of our more technologically innovations are listed below:

 

Automated Mobile Batching Plant

 

In 2000, ACT was awarded the Diavik Diamond Mine Project for the Drilling and Grouting of the A-154 and North Inlet Dikes.

 

The Diavik Diamond Mine is located in one of the most remote and forbidding places in the world, 220 kilometres south of the Arctic Circle and with one single winter road built out of ice and frozen lakes, connects the mine and Yellowknife, the capital of the Canada's Northwest Territories. A seepage cut-off dike had to be built through the lake to separate the mine with the surrounding lake during arctic frozen winter.

 

With the arctic weather challenge, ACT proposed technical requirements of the batching system, and its grouting equipment supplier designed and built an all-weather proof, mobile and fully automated grout batch plant to fulfil this challenging environment. This was the first fully automated grout batch plant in the grouting industry.

 

This plant is a self-contained, mobile, full-size production plant. All equipment is fitted within two roadworthy containers joined as a single movable unit on-site. Electrical power is generated by the main generator and a smaller auxiliary genset is used during non-production hours to maintain heat, light, etc. Once assembled on-site, the plant may tow as a single unit and four independent landing gear mechanisms are used to raise the plant off the running gear and level the plant for production. In addition to the generators, the plant has a compressor, air dryer, furnace, HVAC, lighting, fuel and water storage, and dust collection system. Various agitation tanks, colloidal mixers, progressive cavity pumps, PLC control system, data recording system, and motor control center are used to undertake and record grout production.

 

Cement is delivered via bulk bags to the plant at the bulk-bag unloader which itself, is onboard, but external to the main structure. A powered hoist lifts the bulk bags into the unloader, which supplies the cement feed screw. Other materials, such as bentonite, welan gum, and admixtures, etc. are loaded on board manually/by forklift and water is supplied to the storage tank from external sources, heated, when required. A separate station inside the plant uses a manual colloidal mixer to proportion and premix bentonite, where it is then pumped to two agitated bentonite hydration tanks where it is retained for a given period. When ready, the hydrated bentonite becomes a raw material for grout batching. The two grout agitation tanks serve as the reservoirs for the two Moyno grout pumps, which supply grout in various mixtures at varying pressures and flow rates to the carts. As these tanks are drawn down, the operator may select and assign one of fifteen grout formulas to each cart. This is determined by observing cart pressure and flow rates. A third identical pump is used for water testing and flushing and also serves as a standby for the two main pumps.

 

The on-board control room oversees both automated grout production and monitors and records pumping data at the ‘carts’ positioned externally at the boreholes. Grout batching is fully automated, proportioning water, cement, hydrated bentonite, two admixtures, and Welan Gum. Following mixing, grout is discharged automatically to the assigned grout agitation tank, and the system either re-batches automatically if called, or purges the grout mixer and lines clean, ready for the next batch. Because batching is automated, the operator is generally free to concentrate on pump pressures, flows, and data processing. The operator can see liquid levels of all vessels at all times plus a color touchscreen displays dynamic graphics of the batch process including alarm messages. The Instrumentation system records and prints grouting data using data acquisition modules, a strip-chart-recorder, two Pentium computers and a laser printer.

 

This automated mobile batching plant has also been used for Diavik Diamond Mine A418 dike construction, McCook Reservoir, Wolf Creek Dam, and Center Him Dam projects.

 

SuperCube automated batch plants

 

During the Phase 1b of Clearwater Dam Major Rehab project in 2007, ACT realized its need for a high capacity automated grout batching system due to extreme high grout takes and meeting project schedule. As a result, ACT proposed technical requirements of the batching system, and its grouting equipment supplier designed and built two of the second generation of automated grout batching system called “SuperCube”.

 

“SuperCube” plants are custom fabricated and fully automated via programmable logic control (PLC) and motor control center (MCC) technologies, with available manual batching control, when required. Two plants were custom built for the project. The plants are comprised of the following components:

 

a) Colcrete® SD-1000 high-shear, dual-mill, colloidal mixer, with a batch size capacity of up to 35.3 cubic feet and rated output of 52.8 gpm, equipped with three (3) Rice Lake® 2,425-lb load cells on the mixer unit weigh-frame;

 

b) Two (2) 77 cubic feet agitation tanks equipped with full-contact scrapers at an agitation rate of 15 rpm and in-line grout return line Krohne® electromagnetic flow meters;

 

c) Two (2) 4-stage Moyno® 2000G1-series progressive cavity pumps operated by 15-hp electric motors at a rated output capacity greater than 10.6 CF/minute per pump at maximum pressures of 87 psi per stage (348 psi maximum);

 

d) Two (2) separate liquid admixture addition systems, with maximum rated input flows of 2.6 gpm and 9.6 gpm, respectively, using Verdeflex® peristaltic pumps with in-line Krohne® electromagnetic flow meters capable of +/- 0.5% volumetric accuracies;

 

e) Pre-hydrated bentonite slurry transfer system operated by a Wilden® diaphragm pump with a maximum flow rate of 242 gpm and in-line Krohne® electromagnetic flow meter;

 

f) Water system with a 396 gpm rated pump and 396 gallon capacity aluminum tank; and

 

g) PLC/MMC controllers rated NEMA 4X with a VarTech® 19-inch LCD touch-screen.

 

The two automated batching plants were successfully used for the project, and produced approximately 9,000 CY of grout in 14 months of remaining project.