Magnetic Separation and Filtration of Ferrous Fines and other Contaminants from Fluids Used in Steel Mills
A steel mill uses a large amount of water and other aqueous fluids for a variety of purposes such as cooling, cleaning and lubrication. These fluids play a critical role in the manufacturing process. Throughout the process huge amounts of ferrous scale and fines are generated. There are several areas in the mill where ZGF technology can provide value by removing the contaminants from these fluids.
- Hot Mill
- Scale Removal
- Process/Cooling Water
- Rolling Oil
- Roll Grinding
- Cold Mill
- Rolling Emulsion
- Wet Temper
- Roll Grinding
- Strip Cleaning (prior to Galvanizing, Galv-annealing, Painting, etc.)
- Tension Leveler
- Process/Cooling Water
- Roll Grinding
- Coating / Finishing – Cleaning Section (prior to Galvanizing, Galv-annealing, Painting, etc.)
- Cooling / Process Water
The primary contaminant in most steel mill process fluids is steel; such as steel fines, steel dust, steel particles and steel scale. Other contaminants include oil from lubrication processes, silt, dirt and suspended solids from “mill water” (typically, river water, lake water or well water) and air-borne / atmospheric dirt.
ZGF technology can be installed in a variety of places throughout a steel mill.
The Hot Mill requires effective, efficient, consistent and reliable filtration.
The hot mill does the initial reduction of the steel slab. This process generates an extraordinary amount of ferrous scale and uses large volumes of process water.
To get a better understanding as to where ZGF Maggie, Spring Filter and Tornado technology can provide value in your Hot Mill, click here to download the Process Diagram, Hot Mill / Cold Mill.
Descaling: Process water is used for descaling. High pressure water (1,000 psi – 3,000 psi) is sprayed through nozzle arrangements to break up the scale and remove the oxidized material before the hot roll strip is coiled. It is important to filter the water used for descaling to remove scale and particulate matter that could plug nozzles, and lead to excessive equipment wear and maintenance to the high-pressure pumps.
Typically, all the process water is recycled through a system of scale pits. This approach may be effective at removing large particles, and most of the scale. Some mills have implemented indexing paper bed filters, bag filtration and/or centrifugal separators. Bag filtration and indexing paper bed filtration is inconsistent, and often circumvented at the operator level. With bag filters and media bed filters, there are also additional costs associated with maintenance / labor, as well as, bag / media purchase and disposal.
Centrifugal separators are effective at removing medium to large sized particles (50 - 75 microns, and larger). The ZGF Tornado separator is the future of centrifugal separation technology. The innovative separator utilizes an internal blade design. The blades create a unique and beneficial flow path through the separator that increases the “G – Force”, resulting in more effective and efficient particle removal.
The Tornado is a simple but extremely innovative device. The Tornado has no moving parts and no media. Tornado effectively removes particles without any regular maintenance. If you want to learn more about ZGF Tornado technology, then download the Tornado Product Data Sheet.
To see the Tornado separator in operation, click Tornado animation. The animation shows how the patented blade design results in increased particle velocity and higher applied “G-forces”. As the fluid spins through the length of the separator, the particles are forced to the outer wall to the low velocity solids collection zone at the bottom of the separator. The clean fluid is directed back up and into “clean zone slots” and out the top of the separator.
Effective removal of the smaller fines, scale, dirt and other particulate matter from process water is also extremely critical. Implementation of proper filtration will reduce maintenance costs, improve heat transfer efficiency, and save energy. For removal of these smaller contaminants, ZGF Maggie and Spring Filter technologies provide effective, efficient and environmentally responsible solutions that can help optimize lifecycle costs and minimize the environmental footprint associated with process cooling, a critical hot mill operation.
Rolling Oil
The hot mill also uses rolling oil. The primary purpose of the rolling oil is lubrication. An effective rolling oil can extend roll life, reduce energy and improve the cleanliness of the process.
To realize the benefits of a premium rolling oil, you must effectively remove the contaminants. You can have the best rolling oil; but if you do not remove the scale/fines, you will still have premature roller wear and plugged nozzles. Some mills have implemented indexing paper bed filters, bag filtration, centrifugal separators and/or gravity/bar type magnetic separators. None of these technologies effectively remove the smaller particles/fines. ZGF Maggie technology effectively and efficiently remove the ferrous contaminants from the process.
If you want to learn more about ZGF Maggie technology, then download the Maggie Product Data Sheet or view the Maggie in action by watching the Maggie video.
If you want to learn more about ZGF EZ Clean technology, then click on one of the links to download the Phoenix Product Data Sheet or the EZ Clean EZ700S Product Data Sheet or view the Spring Filter video and see how all the contaminants are removed during backwash when the filter element opens and shimmers.
ZGF technology provides the Hot Mill with the following cost, quality and environmental benefits:
- lower operating costs
- longer equipment & component life
- no consumables & virtually no filter maintenance
- fully automatic 24/7 operation
Product Value increases as it is processed through the Cold Mill. Effective, efficient, consistent and reliable filtration is even more important.
The cold mill reduces the thickness of the hot roll steel via the cold roll reduction process. Throughout the cold reduction process, a significant amount of ferrous scale and ferrous fines are generated.
To get a better understanding as to where ZGF Maggie, Spring Filter and Tornado technology can provide value in your Cold Mill, click here to download the Process Diagram, Hot Mill / Cold Mill.
Rolling Emulsion/Cold Reduction Mill
Rolling emulsion is continuously sprayed on the sheet. The primary purposes of the rolling emulsion are lubrication, cooling and cleaning. An effective rolling emulsion can extend roll life, reduce energy and improve the cleanliness of the process.
A significant portion a cold mill budget is allocated to the purchase of rolling emulsion. To realize the full benefits of a premium rolling emulsion, you must effectively remove the contaminants. You can have the best rolling emulsion, but if you do not remove the scale/fines, you will still have premature roller wear and plugged nozzles, which can negatively impact the quality of the strip. Some mills have implemented indexing paper bed filters, bag filtration, centrifugal separators and/or gravity/bar type magnetic separators. None of these technologies effectively remove the smaller particles/fines.
Effective removal of the smaller fines, scale, dirt and other particulate matter from the rolling emulsion water is critical. Implementation of proper filtration will reduce maintenance costs, improve heat transfer efficiency, and save energy. For removal of these smaller contaminants, ZGF Maggie and Spring Filter technologies provide effective, efficient and environmentally responsible solutions that can help optimize lifecycle costs and minimize the environmental footprint associated with process cooling, a critical hot mill operation.
Wet Temper & Tension Leveler
The temper mill and tension leveler utilize specialty fluids for lubrication, cooling and cleaning. The wet temper and tension leveler are finishing operations. Fluid cleanliness is even more critical in these operations because the steel has already been processed through the cold mill. ZGF technology can effectively and efficiently remove the contaminants from these critical process fluids.
ZGF Technology is uniquely designed to meet fluid cleanliness requirements of the Cold Mill.
Some processes require both magnetic separation and a barrier filter. Your process stream may contain both magnetic and non-magnetic material, such as silt and suspended solids. The EZMAG combines the capabilities of Maggie and EZ900 into a single system with one set of valves, one set of controls, and the footprint of a single system. Reduce system complexity and floor space requirements and save money. The EZMAG is the ideal solution in steel mills.
The EZMAG is the only permanent media, in-line filter that combines magnetic and barrier filtration in a single system. Refer to Maggie and EZ900 for additional information pertaining to these two products. Click here for a detailed EZ MAG specification sheet or EZMAG Product Data Sheet. If you are looking for more information, go to Documents. You can download and access drawings, installation, operation & maintenance (IOM) manuals, as well as other technical and reference documents.
If you want to learn more about ZGF Maggie technology, then download the Maggie Product Data Sheet or view the Maggie in action by watching the Maggie video.
If you want to learn more about ZGF EZ Clean technology, then click on one of the links to download the Phoenix Product Data Sheet or the EZ Clean EZ700S Product Data Sheet, EZ Clean EZ900 Product Data Sheet or view the Spring Filter video and see how all the contaminants are removed during backwash when the filter element opens and shimmers.
ZGF technology provides the Cold Mill with the following cost, quality and environmental benefits:
- lower operating costs
- improved quality
- longer equipment & component life
- no consumables & virtually no filter maintenance
- fully automatic 24/7 operation
ZGF Technology provides the greatest value in Coating and Finishing Operations when quality is critical and product value is high.
Many mills also have value add processes such as galvanizing, galv-annealing, galv-alum and painting. Prior to these coating/finishing processes, the strip must be thoroughly cleaned. The strip is continuously cleaned as it passes through the cleaning section. Cleaning sections are becoming much more advanced as strip cleanliness is becoming more critical as the quality requirements of the finished strip is becoming more stringent. Most cleaning sections have multiple stages including hot water spray sections, alkaline/caustic brush sections and alkaline/caustic spray sections. Each stage requires filtration.
To get a better understanding as to where ZGF Maggie and Spring Filter technology can provide value in your Galvanizing or Painting operations, click here to download the Process Diagram, Steel Mill Finishing Operations.
Manufacturers of cleaning sections do a great job of removing the contaminants from the strip. In older systems, they do a relatively poor job of removing the contaminants from the process. Typically, they would use indexing paper bed filters, bag filtration, centrifugal separators and/or gravity/bar type magnetic separators. None of these technologies effectively remove the smaller particles/fines. Bag filters and indexing paper bed filters do not provide consistent and reliable performance; they require human intervention and are often circumvented at the operator level. Centrifugal separators are not effective at removing particles smaller than 50 - 75 microns.
If the contaminants are not removed from the process, they will redeposit on the strip and render the entire cleaning process ineffective. Less than optimal strip surface cleanliness will result in coating defects and inferior surface finish. Finished product that is off-specification results in a lower saleable price per ton.
The cleanliness of the strip as it enters the zinc pot is a key factor in determining the value of the finished coil. Free iron particles that remain on the strip can create “dross” during the galvanizing process. Dross is created when free iron particles in the galvanizing pot react with the molten zinc. The dross particles can then adhere to the galvanized coating as the steel is lowered or raised from the zinc pot and appear as pimples on the coating. These “dross defects” can significantly reduce the value of a finished coil.
The primary and most problematic contaminant is iron fines. ZGF Maggie technology effectively and efficiently captures and removes the iron particles from the cleaning solution so they can’t redeposit on the strip.
If you want to learn more about ZGF Maggie technology, then download the Maggie Product Data Sheet or view the Maggie in action by watching the Maggie video.
If the contamination is iron fines, broken bristles from the brush scrubber or suspended solids from the mill water, then ZGF Maggie and Spring Filter technologies can effectively and efficiently capture and remove the contaminants from the cleaning solution or rinse solution to prevent redeposition on the strip. Thereby, improving productivity and profitability.
Cleaning section designs vary from line to line. Some lines use mill water in the initial rinse stage. The primary contaminants are silt and suspended solids. The EZ Clean line of automatic filtration systems is the ideal solution.
If you want to learn more about ZGF EZ Clean technology, then click on one of the links to download the Phoenix Product Data Sheet or the EZ Clean EZ700S Product Data Sheet, EZ Clean EZ900 Product Data Sheet or view the Spring Filter video and see how all the contaminants are removed during backwash when the filter element opens and shimmers.
The brush stages may have magnetic and non-magnetic contaminants and require both magnetic separation and a barrier filter. EZ MAG combines the capabilities of Maggie and EZ900 into a single system with one set of valves, one set of controls, and the footprint of a single system. Reduce system complexity and floor space requirements and save money. EZ MAG is the ideal solution in steel mills.
The EZ MAG is the only permanent media, in-line filter that combines magnetic and barrier filtration in a single system. Refer to Maggie and EZ900 for additional information pertaining to these two products. Click here for a detailed EZ MAG specification sheet or EZ MAG Product Data Sheet. If you are looking for more information, go to Documents. You can download and access drawings, installation, operation & maintenance (IOM) manuals, as well as other technical and reference documents.
ZGF technology provides the Cleaning section with the following cost, quality and environmental benefits:
- lower operating costs
- better quality
- longer equipment & component life
- no consumables & virtually no filter maintenance
- fully automatic 24/7 operation
Maintenance and Media-free ZGF Technologies are ideal for Steel Mill Roll Grinding Operations.
Rolls are used throughout the process (i.e. hot mill and cold mill). The rolls wear over time and become out of specification/tolerance. Roll grinding is an off-line process. The roll grinding process ensures that the rolls have the proper tolerances and finish to ensure the coil can meet specification.
Manufacturers of roll grinders are concerned about the functionality of their machines. But they have little concern about removing grinding swarf from the process. They often utilize settling zones to remove the fines/swarf from the metalworking fluid. Settling zones do not remove the swarf from the process, they just defer the problem. Secondary filtration, such as bags, cartridges, or indexing paper bed filters are often added to address the smaller fines. None of these commonly employed methods do a good job of removing the smaller fines from the process. If the contaminants (i.e. fines and swarf) are not effectively removed from the process, the total operating cost of the process will be excessive. Poor contaminant control results in poor surface finish, shorter grinding wheel life, shorter metalworking fluid life, excessive machine component wear, increased maintenance, and excessive waste disposal.
You can have the best machine tools and use the best grinding wheels and metalworking fluid; BUT if you do not remove the contaminants from the process, then you will not realize the full benefits of your investment. ZGF Maggie technology can effectively and efficiently remove the swarf from the grinding fluid.
Effective filtration is essential to:
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Efficient, effective and reliable first pass filtration is critical in grinding operations.
Grinding a 1 ft2 surface can result in chips/fines with a surface area of over 5,000 ft2. If not removed, these fines become smaller and smaller with more surface area and active charge potential with each successive pass through the circulation loop. As the quantity and associated charge of the particles increases, performance and quality decreases, and operating costs rise dramatically.
Roll Grinding machine technology has advanced with better controls and monitoring technology. Premium grinding wheels and grinding coolants are now utilized as surface finish requirements become more critical. However, the benefits of these more advanced roll grinders, and premium fluids and grinding wheels can only be realized if contaminants are effectively removed from the process. With diminishing maintenance staffs and tighter profit margins, contamination control must be capable, consistent and reliable.
The selected filtration technology must be:
- capable of removing small contaminants without negatively impacting the grinding coolant,
- automatic to minimize operator involvement, and
- relatively maintenance free.
ZGF Maggie and Spring Filter technologies meet these purchasing and performance criteria by effectively and efficiently capturing and removing the contaminants from the process.
ZGF technology is:
- fully automatic
- consistent & reliable
- non-disposable
- energy efficient - utilizing a minimal amount of electricity and air during purge/backwash
- able to capture and remove ferrous particles down to 1 micron and non-ferrous particles down to 20 micron
- environmentally responsible – does not generate additional waste, unlike media filters.
- able to reduce defects per unit, fluid usage, and labor while improving quality
Cooling / Process (“Mill”) Water
The source of process (i.e. mill) water can vary. Because process water consumption is so great, mills often look for an inexpensive or free water source such as a lake, reservoir, river, well, or from recycled plant process or wastewater. These water sources can be very high in silt and suspended solids.
The hot mill uses a large amount of water (as much as 75,000 gpm). The water is used primarily for descaling and cooling. A significant amount of ferrous scale is generated throughout the process.
Several processes in the cold mill and in the coating / finishing operations also require cooling. The source for the cooling / process water can be from a lake, reservoir, river, well, or from recycled plant process or wastewater. Some of the water is used for one-pass or once-through cooling, and other water is part of a recirculating system. Whether water is once-through or recirculated back through cooling towers to remove the heat, it is critical to filter the process cooling water to remove scale and particulate matter that could plug nozzles, lines, heat transfer equipment and lead to excessive equipment wear and maintenance.
Process Cooling: “Mill” water is used to cool the finished hot strip, as well as furnace skids, mill rolls and other components. Some of the water is used for one-pass or once-through cooling, and other water is part of a recirculating system. Whether water is once-through or recirculated back through cooling towers to remove the heat, it is critical to filter the incoming process water to remove silt and suspended solids to prevent increased operating costs.
On an increasing basis, the heat laden process cooling water is recirculated back through cooling towers to remove the heat. It is important to filter the process cooling water to remove scale and particulate matter that could plug nozzles, lines, heat transfer equipment and lead to excessive equipment wear and maintenance.
To get a better understanding as to where ZGF Maggie and Spring Filter technology can provide value for your operations requiring process / cooling water click here to download the Process Diagram, Industrial Proces Water or Process Diagram, HVAC / Cooling Water.
The cooling / process water requires filtration! Effective removal of fines, scale, dirt and other particulate matter from process cooling water is critical. Implementation of proper filtration will reduce maintenance costs, improve heat transfer efficiency and save energy. ZGF filtration technology provides an effective, efficient and environmentally responsible solution that can help optimize lifecycle costs and minimize the environmental footprint associated with process cooling which is critical to the manufacturing operation.
Filtration of process cooling water is often overlooked; but cleanliness of the cooling water can have significant impact on mill productivity and profitability. Fouled piping and heat exchange surfaces can result in:
- Higher Energy Costs
- Lower Productivity
- Increased Chemical Costs
- Higher Water Usage, and
- Increased Equipment and Infrastructure Maintenance.
To learn more about how filtration impacts the cost of process cooling equipment and infrastructure, click on the Powerpoint presentation - Impact of Filtration on Process Cooling Water Systems.
ZGF Maggie, Spring Filter & Tornado technologies meet all Steel Mill purchasing and performance criteria by effectively and efficiently capturing and removing the contaminants from the process fluids and process / cooling water.
ZGF technologies will provide value throughout the steel mill.
ZGF technology is:
- fully automatic
- consistent & reliable
- non-disposable
- energy efficient - utilizing a minimal amount of electricity and air during purge/backwash
- able to remove ferrous particles down to 1 micron and non-ferrous particles down to 20 micron
- able to provide value throughout the mill and help optimize each process by effective and efficient contaminant capture and removal
If you want to learn more about ZGF EZ Clean technology, then click on one of the links to download the:
View the Spring Filter video to see how all the contaminants are removed from the Spring Filter during backwash when the filter element opens and shimmers.
If you want to learn more about ZGF Maggie technology, then download the Maggie Product Data Sheet or view the Maggie in action by watching the Maggie video.
The EZMAG is the only permanent media, in-line filter that combines magnetic and barrier filtration in a single system. Click on the links below for additional information.
The Tornado is a simple but extremely innovative device. The Tornado has no moving parts and no media. Tornado effectively removes particles without any regular maintenance. If you want to learn more about ZGF Tornado technology, then download the Tornado Product Data Sheet or click on the Tornado animation link to view the Tornado separator in operation.
ZGF technology provides value
ZGF technology is now considered by many as the best available technology for many applications throughout the mill. As steel mills continue to implement our technology and realize the exceptional value, some organizations have shared their success stories.
Click on Success Stories to jump to the Success Stories / Case Studies page to learn how ZGF technology provides value. Click on the links below to learn how our customers were able to reduce operating costs, improve process reliability and quality, and reduce the environmental footprint of their operations by implementing ZGF technology in their mill.
Simplicity, consistency, reliability and the lowest cost of ownership make ZGF technology the best solution and value for all your steel mill fluids!
ZGF is your preferred partner.
Filtration should not be a burden.
Filtration should be a tool that improves quality and reduces cost.
Let us help you meet your objectives and make your job easier!
ZGF has the experience and dedication to customer satisfaction that you are looking for. Contact us or request a quote today.