Introduction
New Logic Research’s patented VSEP membrane filtration system has been installed at Silica Gel processing plants. Vibrational membrane filtration is an innovative new way to dewater or diafilter silica gel during colloidal silica production. VSEP can be used as a pre-treatment for a spray dryer or evaporator. It can replace other less reliable pre-treatment systems such as Centrifuges. Today’s Industrial Silica market is very competitive and efficiency in operating costs can make a difference. The VSEP system consumes about 12 kW of electricity and can reduce the gas consumption of a spray dryer by an average of 700,000 Therms/year. Also, the power consumption of a VSEP system is 10-20 times lower than Centrifuges.
New Logic’s vibrating Membrane System is currently being used for dewatering of PVC Latex, Paper Coatings, Titanium Dioxide, Latex Paint Wastewater, and many other thick slurries where volume reduction is desired. There are Silica customers who are using VSEP to diafilter the slurry to wash it and remove impurities and salts and for product recovery from wastewater during wash down.
Characteristics
Colloidal Silica comes in many forms and has many unique properties. It has a strange and widespread number of uses. It is used as a viscosity additive for the latex in tennis shoe soles and is also used for de-inking during paper recycling. Colloidal Silica has many unique characteristics that make it useful. The man-made amorphous type has no defined shaped and the surface of the particles has great molecular charge. Just as the coastline of Norway is saturated with fjords giving a very small country one of the largest coastlines in the world, the surface area of amorphous Silica is incredibly large in relation to its size. Silica Gel has a surface area equal to 700m^2/g. Only activated carbon has a higher surface area. Another way to illustrate this is that the surface area of one teaspoon of colloidal Silica gel is equal to more than one football field in size.
Fumed Silica is more densely gathered due to its chemical synthesis process. Silica Gel is a suspension solution of random colloidal silica without definite form or size. The particles in the solution form a loose network due to the “Brownian Motion Theory” which describes the random collision of fluid molecules against the suspended matter. Because the particles repel each other, they are evenly dispersed and will not settle out. In addition, colloidal silica will have very high viscosity and a low gel point. Colloidal Silicas and other Silicates can have Gel points as low as 15-35%. The gel point is the concentration at which the fluid will not flow and cannot be pumped.
Raw Materials
The main ingredient for amorphous silica is regular quartz sand which can be found in abundance anywhere. This sand is processed with Sodium Carbonate, Na2CO3 which is made using the Solvay process combining salt, ammonia, carbon dioxide, and limestone all naturally occurring substances.
Silica Gel Production Process
During the refining process, the colloidal Silica is suspended in a salty aqueous slurry. This slurry must be desalted and dewatered. VSEP is uniquely able to be used as a diafiltration process and then to dewater in a single pass. During diafiltration, a UF membrane is used which will reject the particles and allow the salty water to pass through the membrane. By successive rinses, the silica can be completely separated from the salt solution. The resulting gel is nearly pure colloidal silica with some water.
Colloidal Silica sells for about $25 per Pound. While in production, 2.3 tons of product is recovered each hour per 84” VSEP.
New Logic’s Solution
Technological advances in membrane filtration systems and membranes have created an opportunity for the efficient and economical treatment of Silica Diafiltration and Concentration. The “Vibratory Shear Enhanced Process” or VSEP developed by New Logic makes it possible to filter chemical processing streams without the fouling problems exhibited by conventional membrane systems.
In this case study, the VSEP mem brane system utilizes an Ultrafiltration membrane which will reject the sus pended solids and colloids. New Logic uses over 200 membranes and tighter RO and NF membranes are available.
VSEP is capable of handling thick slurries and concentrating the feed stream to a sludge which can be dried. The filtrate from this can be reused for washdown operations, used as plant water, or sewered. The VSEP can be used by itself or in conjunction with other equipment for a comprehensive treatment system.
Process Description
VSEP is capable of handling influent streams in a single pass with very little pre-treatment. Usually just a 100 mesh prescreen is all that is required. In this case study, the VSEP was used to re place a centrifuge. The Block diagram below shows the treatment system. The raw process feed enters the feed tank at the left of the drawing. From there it goes to a bag filter and then to the VSEP machine itself. The concentrate is returned to the feed tank for successive washes until the conductivity reached the design target at which time it is diverted to the concentrate holding tank for further treatment, The Filtrate is partially reused in washdown operations and partially sewered.
Process Conditions
The membrane treatment system can process at a rate of about 80 GPM (18 m^3/hr). The process feed containing salt is first concentrated to remove the bulk of the water. Then, with the process of washing, water is added and then removed thus diluting and removing the unwanted salts and other dissolved contaminants. The operating conditions are 30ºC at about 80 psi using an Ultra filtration membrane. The footprint of the V✧SEP is about 16 SF (1.5 M^2).
Process Results
This rate of production would be equal to about 105,000 gallons per day. The concentrate produced is about 15% of total solids which is very near Gel Point with extremely high viscosity. This stream is sent for further processing using other equipment. The VSEP is periodically cleaned using a caustic cleaner to reset the flux and produce consistent long-term results.
System Throughput
The VSEP system performance is a function of temperature, % recovery, & % Total Solids in the feed slurry. The more concentrated and colder the feed, the lower the throughput of the VSEP system. Temperature affects the viscosity of the liquid and viscosity affects the liquid fraction’s ability to move through the membrane surface. In general, one 84” VSEP typically produces 60-80 gpm of clean water filtrate from Colloidal Silica at a recovery of 75% of the total volume as permeate.
System Components
The process feed is pulled out of an existing 5000 gal feed tank. The tank is located near to the VSEP and the feed pump of the V✧SEP system can prime with only head pressure from the tank. The liquid transfers through a prescreening unit to remove large particles, (100 mesh). There are many types of mechanical screens that could be used. The picture below shows the type used.
The feed water then flows into a vertical multistage centrifugal feed pump 120 150 which provides the pressure to the Filtration unit. The bag filters and pumps are provided with the VSEP system and are skid mounted for easy installation.
The VSEP system comes with a cleaning tank and many of the valves and other interface equipment. The system is “Plug and Play”. The feed tank, trans fer pumps, heat exchangers, and boiler are not normally included, but can be provided as part of a complete process package. The VSEP system is auto mated and controlled by a PLC (Programmable Logic Controller). Opera tor interface is limited to monitoring the system and making periodic adjustment to parameter settings. The system comes standard with “Foxboro” brand instrumentation including pressure sensors, tank level sensors, flow transmitters, pH analyzers, temperature meters, and conductivity sensors to monitor the process conditions and will send a 4-20 mA digital signal to the PLC for seamless operation.
Conclusion
The implementation of New Logic Research’s VSEP membrane filtration system in Silica Gel processing represents a significant advancement in industrial efficiency and sustainability. By replacing traditional methods such as centrifuges with vibrational membrane technology, VSEP offers superior performance in both diafiltration and dewatering, with dramatically lower energy consumption and operational costs. Its ability to handle thick slurries, recover valuable product, and reduce environmental impact through water reuse makes it an ideal solution for modern Silica Gel production. As the industrial Silica market continues to demand higher efficiency and cleaner processes, VSEP stands out as a proven, scalable, and cost-effective technology that meets these challenges head-on.
Company
New Logic is a privately held company located in Minden, NV. Incorporated in 1986, New Logic manufactures a proprietary membrane filtration system called VSEP ® (for Vibratory Shear Enhanced Processing). Originally developed for blood plasma separation, the technology has been scaled up to meet the growing separation needs for many industries. VSEP can be employed in water treatment, product separation, solids dewatering or wastewater treatment. The industries and applications for VSEP are quite diversified and include: Pulp & Paper (black liquor, whitewater, box plant effluent, end of pipe), Industrial Water Pretreatment (ultrapure, boiler feed, surface water), Pigments & Paint (latex emulsions, product recovery), Mining (mine tailings), Solids Dewatering (calcium carbonate, kaolin clay, TiO ), and Metal Working (oily wastewater, metal hydroxides).
Technical Services
New Logic has years of experience and expertise in membrane filtration. Their 40,000 sq. ft. facility provides comprehensive manufacturing and facilities. Highly trained engineers and technical staff are available to support your application questions. Feasibility testing can be accomplished in-house, or a fleet of pilot units are available to support on-site testing. Operational surveys are available to help assess your needs and potential cost savings. An experienced team of technicians are available to support both on-site pilot work and VSEP system installations.
People
From scientists to customer service associates, New Logic recruits some of the best people available. Academic credentials include doctorates and advanced degrees from such notable universities as Northwestern, Cal Berkeley, UCLA, Johns Hopkins and others.
For more information about how V✧SEP can help you, please contact us at info@vsep.com.
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