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Perchloric Acid Scrubber System

Engineering Expertise for a Diamond Mine in Canada's Far North

Fabricated Plastics' Proprietary Perchloric Acid / NOX Scrubber employs a combination of Spray Absorption and Engineered Mesh Pads.

When Fabricated Plastics Limited of Maple, Ontario was invited to quote on some work for a diamond mining company in Canada's North West Territories, they were naturally intrigued by such a high interest project.

The world of diamonds immediately conjures up exciting thoughts of exotic locations and immense wealth.

In fact, the long, complex and arduous task of identifying diamond deposits, the enormous and risky finance required to exploit the find, the multi task process necessary to


 reduce thousands of tons of rock in order to yield the precious stones is anything but romantic. Rather it is extremely hard work that has no guarantee of success, and is not without risks that are sometimes highly dangerous. It is a tribute to man's ingenuity that over a few centuries, the inherent problems of diamond mining and production, though not entirely overcome, have at least been considerably eased. Mining skills, chemical expertise, enormous leaps in the use of technology, together with advanced engineering techniques and an increased respect for the natural environment, have all played major parts in facilitating diamond production.

After diamondiferous kimberlite has been located and considered desirable in quality and volume, the infrastructure of the mine is built. Eventually the process of removing the rock from the ground begins and, though it varies greatly depending on location, climate, size and other variables, the work basically entails reducing the rock in several stages by using remote controlled jack hammers, jaw crushers and primary roll crushers. This material is then passed through scrubbers before being screened into suitable size fractions. Next, the kimberlite is mixed with water and ferrosilicon sand and cycloned. Diamonds and other heavy minerals migrate to the outer edge of the vortex thus forming the concentrate. Several other processes are used at this point to separate unwanted materials and to create pancakes of manageable size before proceeding to the final stages of complete diamond recovery.

Recently, a large and very valuable diamondiferous kimberlite site was discovered in the North West Territories and it was there that Fabricated Plastics became involved in the business of diamond mining.

The fully equipped Fabridated Plastics Fume Hood and Cabinet includes a recirculation tank and all of the system controls.The project called for a working laboratory that was to be located in a very tight space. It's function was to clean diamonds by removing any remaining materials surrounding them so that they could be graded and passed onto the final stages of cleaning, cutting and polishing. There were three major problems in designing and supplying this equipment.

First, the space problem was so acute that the design required outstanding engineering expertise. The second problem was a contributor to the first in that the processes the equipment was to perform, involved using some of the most toxic agents on the planet. When space limitations are added to the imperative safety demanded by using highly dangerous chemicals, engineering and design skills are severely tested. Third, though the equipment was essentially industrial in nature, it had to look like an immaculate laboratory since it would be a focal point for visiting customers and dignitaries.


Normally, such equipment would be supplied by a laboratory supply company. But it was inappropriate in this instance as such companies only offer a catalogue of components that are assembled to suit the customer's needs. In this case, both the material and space requirements were not manageable by a laboratory supply company. Much of their equipment is made from various metals which would have been entirely wrong when working with volatile acids. In any case, the collection of components needed to create the whole unit far exceeded the restrictions of space available. Finally, the gases created in the process were environmentally unfriendly in the extreme and had to be totally neutralized before being expelled into the atmosphere. In short, it was obvious that this was a task better performed by a skilled engineering company that featured plastics. So it was that Fabricated Plastics was awarded the contract

Fabricated Plastic's design solution to the stringent requirements was made up of the following:

  1. a perchloric acid scrubber with assay fume hood and cabinet

  2. an exhaust system

  3. a recirculation system

  4. a three stage eliminator

  5. a cross flow scrubber

  6. an electronic control panel

The fume hood and the cabinet were made from equipment grade white PVC instead of the usual grey to satisfy the desired finish. The ducts and scrubbers were made from grey PVC as they were installed out of view. The design allowed for a maximum exhaust volume of 1500 CFM.

Because of the perchloric acid and the nitrous oxide (NOX) produced by other acids, the scrubbing and venting design and technique took on an enormous importance. Arguably, perchloric acid is the most aggressive of all acids. If it were to rise up into the ducting and accumulate in a place where it could dry and condense, it would literally have the potential to explode .A simple act such as a maintenance crew adjusting the dampers could be disastrous. NOX is also invasive and a great enemy to the environment. To counteract these negatives an ingenious wash down system was created that sprayed the interior of the ducting and saturated the walls at regular intervals, thus denying the opportunity of a dangerous build up and potential hazard.

Scrubbing fumes like NOX is very difficult but is easily achieved with Fabricated Plastic's proprietary crossflow scrubber. The system was designed to be operated continuously avoiding down time. This feature even included a meter that indicated the pH balance and allowed for a complete scrubbing liquid changeover without interruption.


The Perchloric Acid/NOX Scrubber System was test-assembled in Fabricated Plastics' plant.   diamon5.jpg


The exhaust outlet featured a Michigan stack to stop the elements from entering the system. This was particularly important as the climate in Canada's far north would have frozen the inside of the stack, reducing or completely plugging the exhaust. For this same reason, there could be no wash down inside the stack itself.

Every part of the equipment was made with extreme care so that it was unmarred by a single scratch and maintained its pristine appearance in keeping with laboratory aesthetics. The total package was "trial assembled" in Fabricated Plastic's large plant space and thoroughly tested for fit, finish and instrumentation. With the green light from Fabricated Plastic's Quality Control, it was carefully packaged and shipped to its destination.

Some time later, the customer reported that the equipment performed beyond expectations and that the stack emissions had been tested by an independent agency and actually surpassed the local Ministry of Environment standards.

Diamond mining and production in Canada has mushroomed in the last few years. When the potential of the North West Territories, Northern Alberta, Saskatchewan, Ontario and Quebec are added together, it is possible that Canada will exceed South Africa in volume in the foreseeable future.

Fabricated Plastics was both proud and pleased to have been a part of this exciting venture. It's successful conclusion will no doubt encourage other companies engaged in the increasing diamond mining activity to share in the Fabricated Plastics expertise.

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