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Heavy industry

Control of water solids waste

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Clearing the way from problem to plant

By the application of simple logic, a complex problem is broken down to subquestions with Yes/ No answers. The answers will form the skeleton of a flowsheet. Analysis of water and solids, test work and experience will dimension the unit operations. Metso goes all the way from investigation, process design, equipment manufacturing as well as engineering, plant erection and commissioning. The following is a presentation of some treatment plants designed and commissioned by Metso. If you find a similarity with your problem ­ let's get in touch!

Our people around the world are located close to you, in order to understand the forces that shape your business realities. This empowers us with unique insight to create effective solutions that increases the productivity and environmental quality of your operations.

2 Process systems

Gravity is free of charge. Our strive in solid/liquid separation is to use gravity to its maximum. Lamella sedimentation enables it to be used in a reasonably compact installation. Feed preparation aims to make the material able to be pumped, transform the soluble to solids and to make the solids sink. What gravity may fail to accomplish will be settled by force. E.g. sand filters, magnetic filters or carbon adsorption for liquid purification, vacuum filters, belt filters and press filters for dewatering of solids.

Process systems 3

Iron and steel

Steel plants, in general, operate on a massive scale. Water quantities are big. Solids from furnaces, casting and mills are distinct particles. Straight forward solid liquid separation applies. Traditional handling has been in huge settling basins, pits and filter batteries. The lamella technique, continuous filtration, magnetic filtration and a general care in forming the plant layout, will minimize building volume with maintained availability. Treatment of pickling effluents will call for elaborate treatment of heavy metals and toxins, as described on page 8. Scrubber effluent treatment

The traditional way of scrubber effluent treatment is sedimentation in circular clarifier/thickeners. Erection on legs allows a fit of dewatering and auxiliary equipment in a compact fashion. Typically 1000 m3/h can be treated in a 25 m diameter unit. 4 Process systems

Lamella sedimentation promotes area performance. 700 m3/h of mill effluent is cleaned in one shop fabricated inclined plate settler. Suspended solids in overflow is less than 50 ppm. Underflow is concentrated to 60% dry solids.

Iron bearing contaminants are suited for magnetic trapping. High gradient magnetic filters Metso HGMF®, operate with outstanding filtration rates, over 500 m/h for mill effluents. The extreme magnetic forces achieved also permit removal of weakly magnetic species, such as oxides formed in BOF or vacuum degassing operations.

Continuous casting and hot milling

Use of spiral dewaterers and continuous sand filters replaces orthodox scale-pits, sedimentation basins and back-flush filters in the treatment of water from continuous casting and hot milling. Savings are radical in all aspects ­ space, investment, availability, running costs, maintenance. The spiral dewaterer retrofits scale-pits in existing plants and runs unattended. One modular unit with inserted lamella plates is capable of handling a feed flow bigger than 2000 m3/h. Scale discharge contains just a few percent moisture. The spiral dewaterer does the tough job in separating the material > 0.1 mm. The dewatered oxide scale is dry with a moisture content of approx 5% or less, suitable for conveyor and ladders, profitable for reclamation. Pumping of scale and scrap is simple routine with Metso sump pumps and allows the clean-up system to be freely located. The wear parts in the rigidly designed Metso pumps will in many cases last for years.

Process systems 5

Metals and metallurgy

Heavy metals and toxic compounds are unavoidable in many industrial processes. Toxics may hide in soluble form in a visibly clear effluent. When precipitated, they can be separated as solids.

The poisonous nature of these substances calls for: · Fargoingcirculationofthewater · Elaboratetreatmentofwaterbleedoff · Stabilisationofdisposalproducts · Controlleddisposal · Reclamationofsolidswhenpossible Boliden developed the Kaldo Process for lead production. Based on samples from pilot tests, Metso designed the water treatment process with recycling of both water and solids. The treatment involves stepwise precipitation of heavy metals under controlled conditions, and dewatering and drying of solids for reclamation in the process. The corrosion conditions were severe and met by rubber lining, plastic coating or plastic design of the process equipment.

Scrubber Caldo owen Recycling material

Drumfilter Chemical dosage

Dryer

Clarification Sedimentation Thickening

6 Process systems

Production of ferro-chromium, in carbon/ anthracite electrode furnaces and with coke as reduction medium, may apart from metal fumes give raise to formation of polyaromatic hydrocarbons (PAH) in the furnace gases. The feed, 200 m3/h, is flocculated and clarified in one lamella clarifier/thickener with pH-control. A substantial part of the PAH content is removed already in this step. A maximum part of the water, over 80%, is reused after cooling. The bleed is polished in sand filters and carbon adsorption columns to safeguard effluent standards before stream discharge. The plant runs unattended over a PLC, with automatisation also of chemical dosing, sampling and monitoring.

The use of lamella sedimentation techniques makes the installation of a full process plant in less than the space of a conventional clarifier possible. This plant, se picture to the right, serving the scrubber water system of a kryolite furnace, treats 120 m3/h of water for circulation. Solids, dewatered on a belt drum filter, are bound in concrete blocks for safe disposal. The concrete handling is man operated on daytime whereas the water treatment runs unmanned continuously.

Process systems 7

Energy, chemistry, pulp and paper

There is no fire without smoke, regardless of the source ­ oil, coal, peat, organics. Wet gascleaning will produce water effluents similar to the previously described metallurgical processes.

Water used for heat-transfer is subject to strict demands in quality. Contamination by corrosives from the pipe lines has to be balanced by removal in closed systems. Solids, by-products or residues, may be processed and re-utilized as an integrated part of the chemical process, or as a raw material source, exploiting a waste heap. Condensates from waste residue burning represents the worst case of contamination with toxins such as mercury, cadmium, dioxins, aromatic hydrocarbons. By chemical pre-treatment, clarification, filtration and adsorption, these contaminants are brought down to drinking water levels. The picture beside shows Metso Inclined Plate Settlers for treatment of 800 m3/h of bottom ash cooling water in a coal fired power station. Metso thickeners, filters and pumps are also used for gypsum separation in FGD-plants.

8 Process systems

stood responsible for process guarantees. The SALA-HGMF®, high gradient magnetic filter, here in a nuclear power plant (above), cleans e.g. boiler feed water, condensates in thermal power systems and district heating water at unmatched filter rates. Magnetite removal is close to 100% even at submicron particle sizes. Total iron removal is typically 90-95%. It also removes substantial amounts of copper. It operates at much higher temperatures than any other filter system. It is also insensible to flow variations and permits heavily contaminated condensates. This means increased boiler availability and substantial energy savings. Features · Extremefiltrationrate · Nomovingparts · Longdutytime-over24hbetweenautomatic rinse · Lowpowerconsumption · Highoperatingtemperatures Benefits · Compact · Reliable · Lowmaintenance · Highavailability · Energysavings

The picture below shows a system for cleaning of solids from a landfill, heavily contaminated by sulphur and sulphuric compounds. The treatment involves crushing, grinding, thermal oxidation, flotation and dewatering All equipment is covered and ventilated for odour control. Separated sulphur is reclaimed. Purified soil is returned to landfill. The flowsheet was worked out in close cooperation with the client. Metso demonstrated the process in laboratory and pilot test work, engineered the plant, delivered the equipment and Metso belt drum filter with cake wash for recovery of magnesium oxide in a pulp and paper industry. Also used for fiber/clay and bark/sand dewatering.

Process systems 9

Mining and minerals, sand and soil

Metso has a worldwide reputation as a leading company in the processing of minerals. The heavy and robust handling in this industry has indeed affected the development of Metso equipment design. Treatment of water and residues related to mining, mineral benefication, gravel, sand, soil etc. comes naturally.

Restmoistureindewateredmineralconcentrates can be much reduced by using pressure filtration. The Metso Air Pressure filter type VPA, se picture above, gives 50% lower rest moisture compared to vacuum filtration.

The classical sand treatment separates the minus 63 micron silt from the product. Especially in a large scale the silt disposal will be a nuisance. The simple system shown above separates the silt / sand on a cyclone, concentrates the fines and cleans the water for re-use.

Inclined plate settler, German instatallation 10 Process systems

The call for soil decontamination plants has emerged from the discoveries in recent years, of severe land pollution comitted in the past. The physical / chemical treatment of such deposits will utilize unit processes used in mineral separation. The treatment plants should be mobile to serve various sites. The Metso "Caravan Mill" spring from twenty years experience in the design of mobile plants.

For metallurgical use the sand quality may have to satisfy narrow margins. In this system impurities are liberated from the sand in a Metso scrubber. A Metso screw classifier delivers dewatered sand and, as overflow, water and impurities. Process water is reclaimed in a Metso lamella thickener, rejecting the contaminants as a bottom sludge.

The "Leca.pellet" used in building is produced by pelletizing and burning of clay. Exhausted fines are washed out in off-gas treatment. Wash water is flocculated and reclaimed in one lamella clarifier / thickener. Concentrated solids are dewatered on membrame drum vacuum filter, recycled and fully reclaimed in the furnace.

Reclamationmayrequireagglomeration ofsolids.Metsohasa40-yearsexperience of pelletizing. The Metso micropelletizer is developed for fine solids agglomeration with demands on process stability, self-cleaning and wear. Waste materials are often fine in grain size, and dusting may present a problem in itself. It can be cured by moistening in Metso rotor mixer which is also an ideal equipment for mixing granular solids with each other.

Process systems 11

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Metso Minerals (Sweden) AB Norrängsgatan2,SE-73338Sala,Sweden,Phone:+4622457000,Fax:+4622416950 Metso Minerals Industries, Inc. 2715PleasentValleyRoad,York,PA17402,USA,Phone:+17178438671 Metso Minerals (South Africa) (Pty) Ltd. PrivateBagX2006,Isando,Johannesburg,1600,SouthAfrica,Phone:+27119614000,Fax:+27113972050 Metso Minerals (Australia) Ltd. Level2,1110HayStreet,WestPerth,WA6005,Australia,Phone:+61894205555,Fax:+61893202500 Metso Minerals (India) Pvt Ltd 1thfloor,DLFBuildingNo.10,TowerA,DLFCyberCity,Phase-III,Gurgaon-122002,India,Phone:+911242351541,Fax:+911242351601

Metso Perú S.A. Calle5Nro.144,Urb.IndustrialVulcano,Ate,Lima03,Peru,Phone:+5113134366,Fax:+5113490913 Metso Minerals (Chile) S.A. Av. Los Conquistadores 2758, Piso 3, Providencia, Santiago, Chile, Phone: +56 2 370 2000, Fax: +56 2 370 2039 Metso Brasil Indústria e Comércio Ltda. Av. Independência, 2500 Éden, 18087-101 Sorocaba-SP - Brazil, Phone: +55 15 2102 1300

www.metso.com E-mail: [email protected]

Metso Corporation, Fabianinkatu9A,P.O.Box1220,FI-00101Helsinki,Finland,tel.+35820484100,fax+35820484101,www.metso.com

Subject to alteration without prior notice Brochure No. 1716-09-11-ESBL/Sala-English © 2012 Metso Printed in Sweden

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