Dutch Filtration’s High Quality Flux Calcined Diatomaceous Earth Filter Aid

by | Dec 16, 2019 | Completion fluids, Equipment

Our MaxFlux filter aid is the best available DE filter media for filtration of wellbore clean up fluid / completion fluids. Maxflux allows high flowrates of highly contaminated brines with retention rates between 2-5 micron, resulting in long filtration runs and minimum filter cartridge usage.

Production and Mining of Diatomaceous Earth

Diatomaceous earth is made from the remains of diatoms. Diatoms are microscopic skeletons of organisms aggregated in the residue of rivers, lakes, and oceans. Diatom skeletons are made from out of silicon dioxide. Silica is a natural product, 26% of the earth’s crust consists of silica. The name diatomite implies sedimentary accumulations that have reached considerable thickness and when thick enough, such accumulations consequently may have possible commercial potential. Synonyms for diatomite are diatomaceous earth and kieselghur.

The mining and production of Diatomaceous Earth requires heavy equipment. It is usually mined in open-pit, surface-mines. In surface mining, a variable thickness of earth, needs to be removed; this material may be reused later for reclamation. Once this layer has been removed, the diatomite layer can be removed from the bed.

The stockpiled material is then transported to a large processing plant for crushing, drying, milling and calcining. Crushing is necessary because the pieces can be very big, but after crushing they are the size of a pea. The ore still contains moisture so the ore will be dried in flash dryers. To make the pieces smaller the ore will be milled gently, beacuse it’s very important to keep the structure of the Diatomite. It is also very important the ore is completely pure, a small amount of foreign matter can downgrade the performance of the diatomite. Purities are removed with separators and traps. To make the diatomite harder and more porous the ore is flux calcined in a large rotary kiln.

(source: International Diatomite Producers Association)

Diatomaceous Earth as filter aid with excellent qualities

Characteristics of diatomaceous earth include superior fine structure, low bulk density, and high porosity and big surface area, high absorptive capacity, insulating ability, relative inertness, and high brightness. Because of these qualities Diatomaceous earth (DE) filtering and related equipment are a very good alternative to cartridges because they are able to handle higher flow rates. Dutch Filtration offers Flux Calcined Diatomaceous Earth, this is the highest quality DE offering higher flow rates.

Before Diatomaceous earth can be used as a filter medium, it must be dispersed on a (polypropylene) filter plate or stainless steel filter leaf with filter cloth forming a uniform filter cake. The filter plate or filter leaf (including the cloth) serves principally as the support for the filter aid. However they have a substantial effect on the filtration performance. The size of the opening should be such that the filter aid particles do not pass through but remain in place to build op a filter cake. But at the same time the filter leaf or -plate must only give a minimum resistance to the flow. The material must be able to withstand chemical, pressure and temperature conditions during filtration. Dutch Filtration offers the best quality filter leaves for your applications.

As we mentioned the first step in DE filtration is forming a filter cake, this is called pre-coating. A slurry is made in the tank from filtered liquid and filter aid, at a concentration as low as possible (0,5% for example). The filter aid must be kept in suspension so little agitation is necessary. The precoat is formed by circulating the DE slurry through the filter. The differential pressure should be at least 1 psi during the precoat process. If the precoat process is complete the body feedcycle can start; filter aid is added to the liquid to be filtered. The dosage of the filter aid varies with the solids content and other variables specific to each application.

Diatomaceous Earth (DE) Filtration Equipment

Dutch Filtration has two types of DE filter units namely the Filter Press and the Vertical Pressure Filter unitTo scatter the diatomaceous earth on the filter leaves of the filter press a slurry skid is required. We offer single and double tank slurry mixing skids.

The single skid is the most economical solution, however the double slurry skid offers more benefits. The double slurry skid is equipped with two compartments operating separately. You can use one compartment for pre-coating and one for dosing the DE material.  If you have two filter presses you can operate these with one double slurry mixing skid.
If you have minimal space we offer a dual stackable mixing slurry unit. The skid contains a slurry mixing skid including
air driven pre-coat and body feed pump and two cartridge filter vessels. This skid can be placed on top of a filter press. With this setup you minimize the footprint. We also offer a DE powder handling system for dosing the Diatomaceous Earth into the slurry skid in a safe manner. This unit is equipped with an electric, explosion-proof dosing system. With a single press of a button you can dose a pre-set quantity of Diatomaceous Earth.
filter press can be used in applications such as, completion fluids, workover fluids, gravel pack fluids, wellbore clean up fluids, frac fluids, waste water, process water, surface water intake and (bio) diesel.


Vertical Pressure Leaf DE Filtration Equipment

Another type of DE filter unitis the Vertical Pressure Leaf (VPL)unit . This unit is very compact and all major connections are on one side, ideal for offshore applications. The VPL unit is equipped with a DE mixing tank. This DE Filter Unit can handle high flow rates and has a large filtration area. Due to the large filter area the unit has a long filtration cycle and provides a very low NTU output. Cake discharge is performed through a closed system with a semi-automatic wash down system, you can also choose not to include this option. The vertical pressure leaves are stainless steel 316 (SS316L) with a polypropylene filter cloth.
The VPL can be designed and manufactured with an integrated duplex filter unit offering minimum footprint. Another option is the double execution of the VPL in one frame offering more filtration surface or continuousfiltration.

The VPL can be used in different applications in the oil and gas industry such as completion and workover fluids, gravel pack fluids, wellbore clean upfluids, surface water intake, process water and wastewater and (bio)diesel.

For additional information about our DE Filtration Equipment and/or our DE material please contact us.

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