SOME APPLICATIONS OF EXPLOSIVE METALWORKING FOR ALUMINUM INDUSTRY

1. SOME APPLICATIONS OF EXPLOSIVE METALWORKING FOR ALUMINUM INDUSTRY A.Z.Bogunov, A.A.Kuzovnikov JSC « Pulse technologies » 660036, Krasnoyarsk, Russia, POB 26780, e-mail: limom1@yandex.ru 1 1

2. JSC «Pulse technologies» • Fabrication of the steel-aluminum transition inserts for anode holder of aluminum electrolyzer. • Developed technology of explosive welding with dovetail type bond of connection. • About 120 000 steel-aluminum inserts were manufactured and delivered for aluminum industry.

3. Objectives for explosive metalworking Decrease of voltagedrop Bimetallic inserts Cooling of Shell Detachable Contact joint Treatment of cathode bar for recycling Connection of bus bar

4. Removal the cast-iron coating from cathode bar1 Сathode bar with coating White cast iron, thickness 10-15 mm Welding at the casting place Сathode bar casting by melting cast iron at blocks Steel Cast-iron Cast iron, thickness20-25 mm Used cathode bar with cast iron coating

5. Packaged ammonite№6 Removing cast iron coating from cathode barfor recycling2 Recyclingcathode bar 1.Chippingcast iron at the side and at the bottom, HEcharge 1,6 kg/m 2.Partial removal from casting side, HEcharge 1 kg/m 3.Milling welding patch Base cathodebar • High economic efficiency • There are problems with nonflat geometry • of used cathode bar

6. Iron cathode- descentdetachable connections 1 – copper aluminum contact; 2 – contact copper layer; 3 – flexible multilayer descent; 4 – cathode bus bar; 5 – cathode bar; 6 – hardware. Contact1 Copper 5mm, aluminum 50mm Contact 2 Copper2mm, aluminum40mm

7. Anode descents for electrolizer with side current leads ConnectionCu – Al is made by explosive welding instead of fusion welding: • High reliability of connection • Substantial reductionof copper consumption Option1: Aluminum with thickness 30 – 40 mmwas welded at the end of copper strip with thickness 10 mm Option2: Aluminum with thickness10 – 20mmwas welded overlapping at the 1/3 copper strip with thickness 10 mm

8. Split connection anode rod – anode bus bar ContactAl – Al was changed by contactCu - Cu Contact copper-aluminumplates aremounted on anode bus bar, copper 2mm Copper coating at the side surface of the anode rod, copper 2mm

9. Bimetal contacts with riffled surface1 Different types of copper surface asperitieson aluminum base, size 2 mm • Surface asperitiesare made from more • hard material than base • Asperities are penetrated into • the opposite surface and cut through • the oxide films • Eliminatingof the stateof the contact surface (non-flatness,roughness, contamination) influence Titanium surface asperities on the aluminum base, size 0,35mm

10. Bimetal contacts with riffled surface2 Voltage drop-contact pressure dependence Processing concept of contact with riffled surface U, mV 30x30mm, current 100А Flat surface SS-Al Ni-Al • Udecreasein 20 – 50 timesfor pure contact and in 50 -100 times for • contamination contact • Uhas inverse proportionality • asperitiessize • At the small loadingUfor pyramid • type asperitiesin 2 timessmaller • than for stripe asperities Riffled surface,asperities 2 mm Р, KPa

11. Bimetal cooling ribs of pot shell Stimulation of electrolysis process of aluminumproduction (pat.RF2322682) Steel-aluminum cooling ribs • Working temperature 4000С • Life time – more than 5 years Option 2: Transition piecesAl 10 mm – Ti 0,5mm – steel 20mm, dovetail connection Option 1: Explosive welding fabricated rib

12. Explosive welding on a base of detonation cord Cutoffs of detonation cord 10 g/m, diam.5 mm Bridge connections aluminum bus bar1 • The works must de done at the shop • conditions • Minimal HE charge • Explosive localizer is a part of charge • construction. Stationary detonationD ≈ 3,5 кm/s HE consumption: Al 5mm (2 plate) – 0,05 g/сm2 Al 15mm – 0,1 g/сm2 Tensile strength 80-110 МРа, waveless bond

13. Bridge connections aluminum bus bar2 L – likes connection , thickness of bridge 10 mm Overlapping connection bus bar, 2 bridges with thickness 15 mm Bridge bus bar butt connection, 2 bridges with thickness 15 mm

14. Standoff Busbar Busbar Insert with bore filled by HE D Wave bond (Ammonite №6) Butt connection thick aluminum bus bar • Works must be done at the shop • conditions • Minimal HE charge • Bus bar thickness– 80 mm • Not overlapping connection HE consumption: Detonation cord - 0,25 g/сm2 Ammonite №6 – (0,1-0,13) g/сm2 Average tensilestrength 40 MРа Bore (5,5–6) mm Standoff (0,5-1) mm Welding region

15. Conclusion Usedcathodebars mounted in a block by pouring cast iron may be cleaned by the explosion for recycling. Bimetallic contacts with the riffled surface can provide a significant reduction in the voltage drop in high-current connections. Different versions of bimetallic cooling ribs of pot shellwere developed for intensification of aluminum electrolysis. Explosive charges on the basis of detonation cord provide welding of thick aluminum up to 15 mm for the bridgeconnection of aluminum bus bar. The technology for the butt connections of thick aluminum bus bar was developed.

16. Thank for your attention