EDUCTOR AGITATION FOR HEAVY NICKEL DEPOSITION: A CASE STUDY.

1. EDUCTOR AGITATION FOR HEAVY NICKEL DEPOSITION: A CASE STUDY. DAVID GABE LOUGHBOROUGH UNIVERSITY and CLIVE PORTER Formerly DOWDING and MILLS LTD.

2. A sponsored research project for the MSc course in Surface Engineering.Nottingham � Loughborough � Hull - Sheffield Hallam Universities

3. MANAGEMENT OBJECTIVES Focus on refurbished marine engine components To improve the process throughput and production rates To improve the product quality

4. PURPOSE OF PROJECT To obtain data to justify the installation of eductor agitation To improve plant instrumentation and to monitor the enhanced process To establish criteria to measure the degree of process enhancement

5. PRESENTATION CONTENTS Design of an Eductor system Some performance parameters Bonuses

6. DESIGN OF EDUCTOR SYSTEM Tank and pump sizing Eductor numbers and placement System costing Commissioning Benchmarking Optimization Monitoring

7. INSTALLATION 6000l tank having air agitation Total agitation flow of 4000l/min Pumped vol. of 800l/min Pump size; 2.2kW three-phase 20 x 3/8in eductors, 5 each side Eductors mounted in swivel tubes System costing (2002): �2509

8. TANK PREPARATION Both air and eductor agitation were retained for comparisons Thorough cleaning vital! Any residual sludge is highly abrasive. Additional ammeters needed for independent current monitoring

9. BENCHMARKING Air agitation alone Eductors alone Eductors at several swivel angles Use of test panels jigged at various positions in the tank Test panels thoroughly thickness tested over whole surface

10. PATTERN OF AGITATION Agitation observed using air bubble entrainment The installation was modelled before use using clean water and good lighting Each bank of eductors was adjustable for angle of jetting

11. DEPOSITION RATES(Watts nickel) Air agitation 3.709g/hr Eductor agitation (30�) 4.527* Optimized eductors 5.054* * Increases of 22% and 36.3% respectively

12. THICKNESS VARIANCE Agitation Time for 0.2mm Corner excess, type mm. Air 22 hr 0.8 Eductors 8 hr 48 min 0.24* Optimized eductors 6 hr 17 min 0.0575* *Waste improvements of 70% and 92% respectively

13. THICKNESS DISTRIBUTIONS Criterion Air Eductors Optimized Wt. gain(g): eductor 20.4 24.9 27.8 Thickness(mm): Corners 0.25 0.275 0.225 Centre 0.05 0.125 0.175 Variance 0.2 0.15 0.075

14. EDUCTOR ADVANTAGES(Gabe, Ward* and Porter** using Cu* and Ni**) Agitation Enhancement over air: 7-10x Deposition rate improvement: 36% Shorter process times: 71% Reduced thickness variability: 92%

15. EDUCTOR BONUSES Zero fume emission Reduced power usage in tank (ie. no insulative air bubbles) worth 1-2V or ~25% per tank Reduction in sludge production (ie no oxidising air) and condensate Reduced additive consumption Saving of heating energy with no fume losses: 10-20%

16. AIRBORNE EMISSIONS* AIR 0.5-1.0mg nickel per m3 air volume EDUCTORS 0 *Draeger tube emission measurements

17. EDUCTORS AND PROCESS FUME Process fume is substantially created by the gas phase and its release at the surface Affected by surfactants and mist suppressants The fume consists of a solvent/solute mist Use of Eductors eliminates 95% of the mist Only public domain data is for nickel electroplating (see Porter and Gabe, Plating & SF 2005). Ni content of Eductor fume was practically zero. Fume carries heat; heat losses can be reduced

18. PROCESS SLUDGE Process sludge is produced by oxidation of dissolved metal and organic additives, and precipitation. Agitative air is the oxidation medium and eductors eliminate this source of sludge. Anodic oxidation of additives is primarily an anode material problem. Choice of anode can be an issue.

19. CONCLUSIONS Increased rates of production and improved film thickness distribution Saving of power usage to offset increased pumping costs A reduction in oxidation and sludge formation; reduced fume and heat losses Technology also useful for cleaning, pickling, etching, rinsing etc.