Elex Precipitators Refurbished for Impala Platinum

Three existing Elex electrostatic precipitators are being refurbished by Bateman Engineered Technologies, a BATEMAN division, at the Phokeng site, Rustenburg, RSA of Impala Platinum Limited Materials Processes. The old units have been in operation for 32 years and a minimum life expectancy of 20 years is specified for the refurbished units.
 


The exhaust duct from the Elex precipitator connected to the exhaust fan, from where emissions are discharged to the stack.

The precipitators recover the precious metals emitted from the furnaces and it is vital that the collection efficiencies are maximised. The units also have to cope with a variable throughput of articulate platinum and platinum group metals and compounds.

A project requirement is that the emissions from the stacks be less than 50 mg/Nm3, a level 50 % lower than that maintained by the old precipitators; the new level is also well below current legislated emission control requirements.

The use of the old casings, which contained two-field systems providing collection efficiencies adequate three decades ago, I composed a design limitation. Two-field systems had to be used again necessitating a complex redesign of the precipitator to enable a maximum collection surface to be packed into the existing casings.

Work on this fixed price contract commenced in April 1999 and the first unit was refurbished and tested by January 2000.Isokinetic in- and outlet testing of the first unit confirmed that it was operating well within specification and the emissions from the stack itself have been measured at 2,7 mg/Am3,with the new unit handling 90 % of the incoming dust. Once all the units are operational, this figure will improve significantly as the dust will be distributed evenly amongst ll the precipitators.

Besides BATEMAN’s design capability incorporating up-to-date Elex technology, a major contribution to this achievement is its experience in the in-house manufacture and on-site installation of the components.

The maintenance of close physical tolerances for platework in electrostatic precipitators is a very important factor in determining collection efficiencies. The project s scheduled for completion in April 2001.

The first of three BATEMAN-ELEX electrostatic precipitators refurbished for Impala Platinum Limited, Rustenburg, RSA. The outlet duct can be seen emerging from the side of the precipitator.

The outlet ducting and stack of the Elex precipitator at Samancor, Mamatwan.

Samancor Installs a BATEMAN-ELEX Precipitator 

A BATEMAN-ELEX electrostatic precipitator has been installed on Samancor’s Mamatwan site by Bateman Engineered Technologies, a division of BATEMAN. The new unit enables Samancor to increase manganese production from the plant’s existings inter-strand to 1m t/yr of sintered product. The plant produces two grades of sinter, a standard grade with a manganese content of 34,5 % and a high grade with 48,0 %.



Samancor’s BATEMAN-ELEX electrostatic precipitator at Mamatwan about three months after commissioning. No fumes can be seen emerging from the stack.

The precipitator is a three-field unit, custom designed to handle 157,56 Am 3/sec of dust and gas emerging from the sinter plant at 240°C, with a contractual guarantee that emissions from the stack will be no more than 100mg/Nm3. It has performed well within specification from the outset and under operating conditions the level of emissions has been measured at less than 50mg/Nm3.

The project grew out of a model study on the existing installation and design in accordance with Samancor’s specifications. BATEMAN undertook the entire turnkey installation, from design to commissioning the precipitator and its programmable logic control (PLC) system, ducting, drives and dust conveying systems.

The BATEMAN team allocated to the project has extensive experience in the application of this technology, from design to detailed engineering, fabrication, delivery to site, erection and commissioning. The Mamatwan site is in North West Province, RSA, north-west of Kimberley. The fabricated parts were transported some 1 000 km by road from the factory in Johannesburg.

The project commenced in January 1997 and was completed in July 1999.

Chrome International’s BATEMAN-ELEX electrostatic precipitator at Newcastle, RSA.

The collection hoppers can be seen underneath the precipitator. The inlet ducting from the kiln is on the right of the picture
and the ducting to the
flue stack is on the left.

 
Chrome International’s BATEMAN-ELEX precipitator

Bateman Engineered Technologies, a division of BATEMAN, has supplied a four-field BATEMAN-ELEX electrostatic precipitator to Chrome International South Africa, owned jointly by Dow Chemicals and Bayer AG. The unit has been installed at the company’s new sodium dichromate production plant in Newcastle, KwaZulu Natal, RSA.

The precipitator is fed with 70 000 t/yr of dry sodium dichromate and 11 000 t/yr of dry chromic acid produced in the rotary kiln. The final emissions from the stack have been officially tested at less than 1 mg/Nm3 of product, a level of efficiency thought never to have been achieved by an electrostatic precipitator before!

This achievement is due to several factors. The latest Elex design technology incorporating improved electronic control was used. Emphasis was placed on ensuring uniform gas distribution throughout the unit and maximising the use of the space available in the casing of the precipitator. BATEMAN’s extensive experience in the application of this technology also resulted in special care being taken during manufacture and erection; this is essential for attaining the highest possible collection efficiency.

Still-air testing prior to commissioning confirmed that the electrical clearances between the precipitator plates were better than the standard specifications set out by the World Precipitator Body. These standards also permit a 20 % tolerance in gas flow through the plates; the variance in flow in the unit supplied to Chrome International is as low as 5 %.

A four-field system was selected for this application as the design studies, which take account of the electrical resistivity and size of the dust particles, indicated that a fourth field was required to correct for the fineness of the dust. The dust adhering to the positively charged plates is released into the collection hoppers by mechanical rapping of the plates. Because of the insulation of the casing the operation of the precipitator is virtually silent.

In addition to the installation of the precipitator, the project also included the provision of the ducting and dust handling systems. BATEMAN undertook all the work for this turnkey installation, from design, detailed engineering, manufacturing, and erection to commissioning. The design commenced at the start of 1998 and the unit was completed and tested in September 1999.

 

Electrostatic precipitator at Hartley

The off-gas cleaning system installed by ELB-Brandt Contracting (Pty) Ltd, a BATEMAN subsidiary, at Zimbabwe's Hartley Platinum Mine has been commissioned and its cleaning efficiency is exceeding its design specifications. The dust emissions from the flue were measured at less than 15 mg/Nm 3 , well below the level of 30 mg/Nm 3 specified in the contract.

This achievement is due to the novel design of the three-field ELEX electrostatic precipitator. Designed and built in South Africa to the standards of ELEX, Switzerland, it is one of a generation of systems developed to meet the new 'Green Environmental Coding'. It enables electrostatic precipitators to reduce dust emissions to levels previously only attainable using bag-houses. The Hartley unit is the third of this new generation of electrostatic precipitators to be supplied under the ELEX banner.

This contract awarded by BHP Minerals Zimbabwe (Pty) Ltd included all of the ducting from the furnace and the converters, support structures and exhaust fans. Work commenced in March 1995 and was completed this April well ahead of schedule.

 

Initial construction of the BATEMAN-Elex
precipitators, showing the
dust collection hoppers
resting on the support structure.

The final result –
Electrostatic Precipitator,
two induced-draft fans, a
glass-reinforced-plastic
stack and the
interconnecting
ducting.

Largest electrostatic precipitator to date commissioned at Impala

The largest BATEMAN-ELEX electrostatic precipitator installed to date by BATEMAN has been commissioned at Impala Platinum Limited Mineral Processes’ Phokeng site near Rustenburg. With a structural height of over 30 m, the precipitator is the fifteenth such project to be completed by BATEMAN for Impala.

In terms of a contract for the supply of a hot-gas cleaning system to recover the product emissions from a spray-concentrate drier at Impala, BATEMAN designed, fabricated, supplied, installed and commissioned the precipitator, as well as two induced-draft fans, a glass-reinforced-plastic stack and the interconnecting ducting.

“The precipitator recovers the product from dust-laden gas from a 50 t/h drier and has outlet emission levels of less than the guaranteed design parameter of 30 mg/Nm3,” reports BATEMAN Project Engineer, Woitek Liberda. “To achieve this, we designed a three-field electrostatic precipitator based on the latest ELEX technology. Such high collection efficiencies can only be achieved with the use of equipment that allows close physical tolerances between the discharge and collecting electrodes. In addition, the equipment was designed specifically to operate at the higher temperatures encountered in a smelting operation such as at Impala, without any distortion of the electrodes occurring.”

BATEMAN has supplied all of Impala’s precipitators. It was awarded this latest project in late November 2001 and completed it in one month less than the 12-month period projected for the supply of a precipitator of
this size.

BATEMAN-ELEX electrostatic precipitators can operate at temperatures of up to 450°C, can handle wet and dry dusts equally effectively and offer low energy consumption and spares cost. The largest BATEMAN-ELEX electrostatic precipitator installed to date by BATEMAN has been commissioned at Impala Platinum Limited Mineral Processes’ Phokeng site near Rustenburg. With a structural height of over 30 m, the precipitator is the fifteenth such project to be completed by BATEMAN for Impala. Largest electrostatic precipitator to date commissioned at Impala Initial construction of the BATEMAN-Elex precipitators, showing the dust-collection hoppers resting on the support structure.

 

The two induced-draft fans have been installed on the left of the new precipitator. An existing BATEMAN Elex precipitator and its stack, with
clean emissions, may be seen in the background. This unit is cleaning gas from a drier similar to the one the new precipitator will be handling.

Impala Platinum orders an electrostatic precipitator

BATEMAN is supplying a hot-gas cleaning system to control the emissions from a spray concentrate drier at the Phokeng site of Impala Platinum Limited Mineral Processes near Rustenburg, RSA. In terms of the contract, BATEMAN will design, fabricate, supply, install and commission the electrostatic precipitator as well as two induced-draft fans, a glass-reinforced-plastic (GRP) stack and the interconnecting ducting.

The precipitator will clean the dust laden gas from the 60 t/h drier to Impala’s specification for outlet emissions at less than 30 mg/Nm3. To achieve this strict limit BATEMAN will install a three-field electrostatic precipitator based on the latest Elex technology.

These high collection efficiencies are only possible using the most advanced equipment in which the close physical tolerances between the discharge and collecting electrodes can be maintained. BATEMAN will thus be calling upon the vast experience of its dedicated precipitator team during the design, in-house manufacture and on site installation of the components.

At Impala’s request the project is being fast tracked and will be completed in 10 months instead of the 12 months usually required for this type of installation. BATEMAN’s electrostatic-precipitator project and erection teams have to date successfully completed many similar projects.

 

 

Two BATEMAN-Simatek pulse-jet bagfilters with 10 m filterbags operating at 160 °C at a rock-smelting furnace producing mineral wool.

The filterbag cleaning
mechanism of a
BATEMAN-Simatek
pulse-jet bagfilter.

A BATEMAN-Simatek
pulse-jet bagfilter.

BATEMAN-Simatek’s particulate- and dry-scrubbing technology

BATEMAN has a co-operation agreement with the Simatek Group, Denmark, to represent the Simatek range of products in the Southern African region. This pulsed fabric-filter technology cleans the filter bags individually and can be combined with a sorption system for semi-dry- and dry- scrubbing of gases. It has been used and proven worldwide in both gaseous- and particulate-cleaning applications.

Proven in many applications, the BATEMAN-Simatek technology offers major advantages over conventional dry- and wet-scrubbing systems. It is easy to operate and the capital, operational and maintenance costs of the installation are much lower than in conventional dry- and wet- scrubbing systems.

The technology utilises a unique patented method in which low-pressure pulses clean the individual filterbags. This is combined with a large air volume to provide a high-energy solution which uniformly cleans filterbags up to 11 m long. The BATEMAN-Simatek bagfilter is used for particulate removal in agricultural, food processing, plastics, glass and metallurgical applications.

The product range also includes the BATEMAN-Simatek’s clean-in-place (CIP) self-cleaning wet bagfilter, used mainly in the dairy industry to remove airborne particulate material. The filterbags are washed and disinfected in situ to clean and sterilise them and prevent the buildup and spread of bacteria in this highly-controlled hygienic environment.

Besides filtering airborne particles, BATEMAN-Simatek’s dry-flue-gas cleaning process removes acidic gases such as HCl, SOx and HF, using a dry and semi-dry absorption system and removes heavy metals and dioxins using an adsorption system. This process is utilised extensively on incineration plants burning a variety of fuels such as oil, biofuels and household, chemical or hospital wastes, including sludge.

In all the plants installed to date, the emissions of harmful substances in the flue gas are well below the European emission standards.

 

Mozal orders bucket elevators and bag filters

F.C.B. Groupe Fives Lille has awarded Bateman Materials Handling Limited contracts for the supply of bag filters and bucket elevators to the new Mozal Aluminium Smelter in Mozambique.

Bag filters

BATEMAN will also supply BATEMAN reverse-pulse bag filters for the green anode handling plant. The bag filters will incorporate the latest design and manufacturing techniques to provide F.C.B. with cost-effective high-efficiency dust control specifically designed to meet F.C.B.’s unique requirements.

The bag filters will handle a total of 64 500 m 3 /h of dust laden air generated in the processing of coke and and will
contain emissions at 10 m 3 /h. These systems have been designed to operate continuously 24 h/day all year under arduous conditions.

Bucket elevators

BATEMAN will design, manufacture and supply three BATEMAN-Brandt bucket elevators for the anode plant at the new smelter. These elevators are similar in design to a number of elevators previously supplied to the Alusaf Hillside Smelter at Richards Bay, RSA, which have been operating successfully for several years.

The BATEMAN-Brandt elevators lift product some 30 m and are of the continuous bucket design, which enables slow running for minimum wear and degradation of the product. They are fitted with specially cast continuous type aluminium buckets. The elevators handle up to 52 t/h of various products, including baked butts, green scalps and highly abrasive petroleum coke.

A close-up view of the new ceramic-filter plant.

Sasol Polymer’s BATEMAN Schumacher ceramic-filter plants in Sasolburg, RSA.
The new unit is on the left alongside the units which were supplied in 1995.

Ceramic filter for Sasol Polymers

Another Bateman Schumacher ceramic filter plant has been supplied to the Sasol Polymers plant in Sasolburg, RSA, to double the brine filtration capacity at the plant. Two similar plants were supplied in 1995 by BATEMAN and have been operating continuously since then, one online and one on standby. The new plant will enable two units to be online at any time, with one on standby.

In this type of configuration, reliability is essential. This is a strong feature of Bateman Schumacher ceramic filters in which the filtration process is fully automatic with long cycle times. The filter elements are precoated and this, together with the enhanced flush- and back-washing operation, prevents clogging of the elements and results in life spans of up to ten years. Filter elements manufactured from technically pure carbon have excellent resistance to the effects of hot salt solutions.

At Sasol Polymers a brine with a low suspended-solids content is required to protect and extend the life of downstream ion-exchange resins and membranes. The brine feed to the filter plant contains about 300 g/l of salt and between 10 and 50 ppm of suspended solids. Operating at a pressure of 5 bar, the total continuous output of the plant is now 130 m3/h of high-quality filtered brine, containing less than 0,5 ppm of particles bigger than 0,3 micron. It operates on a 48 h filter cycle, but this is reduced if the pressure differential of inlet and outlet streams exceeds 2 bar.

The sintered ceramic technology embodied in the Bateman Schumacher plants was developed in Germany and Japan by Schumacher and more than 300 units have already been installed worldwide.

The order for the Bateman Schumacher ceramic filter was placed in March 2001 and the unit was delivered to site in September 2001. It is operating as per specification.