Monometer Melting and Refining Rotary Furnaces

A new Monometer copper melting rotary furnace is scheduled to be installed in Africa this Autumn. Facilities at the plant will equip the installation to meet European standards for emissions abatement, and the furnace technology will enable the client to cast specification ingot from all grades of scrap while melting with low-cost reclaimed oil.

The furnace will be one from the Monometer range of economical units with capacity between 1 and 2 tonnes designed for thermal and metallurgical efficiency where smaller batch production is preferred.

Monometer equipment in the UK continues to provide foundries with the competitive versatility to produce a range of specification product from all grades of scrap material. For example, the popular Monometer 5 to 7 tonne capacity rotary furnace cycles in around 3 hours 30 minutes with a lining life in the region of 220 heats. Alloys commonly produced range fro

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LG1, LG2 through to the higher grades CT1 and the phosphor bronzes. Further products and high purity copper is obtainable from the furnace’s Monometer refining technology.

For refining, the furnace is equipped with programmable gas diffusion refining technology, and variable chemistry main burner. The variable flame chemistry is designed also to protect the molten bath from oxidation, so to allow effective protection with minimal slag volume production and in the absence of any slag covering.

Image: Specification copper ingot production from Monometer Rotary Furnace

Various rotary melting processes have incorporated Monometer refining equipment, including iron, copper and lead, performing significantly above traditional methods in terms of increased yield, thermal efficiency and furnace productivity.    

For example, in copper refining from Birch-Cliff to high purity copper, a 6-tonne capacity Monometer tilting rotary furnace will typically cycle in 4 - 6 hours; 3 tonnes of scrap iron may be melted, alloyed and tapped in under 120 minutes, and 10 tonnes lead battery scrap may be processed through the furnace in under 5 hours.  Monometer designs and supply includes the furnace charging system, gas diffusion technology for the refining process, slag systems, oxy-fuel burner system, and exhaust filter complete with settler, as well as the fluxing agents injector, and consumable spare parts.

Monometer offers comprehensive onsite support, ranging from turnkey management or installation support, to short training packages targeting metallurgical training or general furnace performance. All Monometer clients benefit from being kept up to date with the latest equipment software updates and full engineering on site support.

For more information on this or Monometer products please contact Dr Christopher Hall PhD, FICME, Monometer Holdings Ltd, Monometer House, Rectory Grove, Leigh-on-Sea, Essex SS9 2HN Tel +44 (0)1702  472201 Fax +44 (0)1702 715112

Email c.hall@monometer.co.uk

Website www.monometer.co.uk

Monometer was approached by West Country Tiling to comment upon and try to resolve reoccurring failures in their furnace crucible, and a variable melting performance. The furnace in question was a 1-tonne lead capacity crucible supplied by another company.

A very interesting and complimentary video was also included from the client showing their production and manufacture of lead-roof sheeting.  http://www.youtube.com/watch?v=YxywudfRvTE

Monometer assessed the furnace design including burner system, together with the process requirements.

Following investigation, several problem areas were identified including:

• Localized spot heating of a restricted area of the crucible that was causing damage to the crucible fabrication,

• Natural vulnerability of the fabrication to thermal stress was exacerbating premature crucible failure,

• The air gap between furnace brickwork and crucible was insufficient to allow necessary flame circulation for distribution of heating around the crucible.

• The effect of the burner angular position combined with proximity to the exhaust resulted in hot combustion gases traveling mainly straight from burner to exhaust without proper circulation around the crucible.

Furnace modifications were therefore advised as follows:

• Angular re-positioning of the burner with respect to the crucible for the purpose of promoting circulation of flame around the crucible and eliminating as far as possible localized spot heating.

• Burner repositioning with respect to the exhaust, so to promote circulation to the longest possible path prior to exhaustion.  

• Reduced firing rate

• Replacement of the fabricated crucible with a smaller redesigned cast iron crucible for the purpose of improved melting performance and crucible life. The smaller crucible was to allow an increased gap between the furnace brickwork and crucible to allow hot gas circulation around the crucible; the cast iron construction was to promote heat transfer both around and through the crucible to the charge materials within and to eliminate vulnerability to thermal stresses.

All recommendations were implemented by the client, and ultimately the melt time was considerably reduced, fuel efficiency increased in proportion to the reduced melt cycle time and following a reduced normal firing rate, and issues concerning crucible longevity and reliability were entirely eliminated.

Attractive economy of the work required to implement the proposed solutions was achieved by the client carrying out fabrication work locally and since the majority of the existing burner fabrication was reused and constituent parts retained. Additionally, Monometer was able to supply a competitively priced made-to-measure bottom-pouring cast iron crucible.

After the furnace modifications at West Country Tiling had been completed, and the new pot had been fitted, Toby Pitt commented “Despite my unnecessary worrying the outcome is perfect.  Thank you”.

Monometer welcomes enquires for new furnace equipment as well as for assisting with updating or problem-solving performance issues whether process or furnace related.