MNTAP Un- of MhnesotP in Minnesotc (eoq 247a Summer Intern Report

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1 ... ' - - c? JL\J. PDF MNTAP MNNESOTA TECHNCAL ASSlSTANCE PROGRAM Un- of MhnesotP in Minnesotc (eoq 247a15 W-lC3 soy" Haplth Secvice Executive Summary Twin Cltlea AM (61'2~ MlMupolk MlnnesotP W 1986 Summer ntern Report Options for Waste Reduction in Circuit Board Fabrication in a Small Captive Shop By Terry Foecke. Project Conducted at Telex Communications nc., LeSueur, MN Telex-LeSueur manufactures film and slide projectors as a division of Telex Communications, nc. t employs 120 people full-time, and has recently absorbed operations performed at another facility in New York. As part of its manufacturing operation, Telex-LeSueur fabricates circuit boards for use in its own production. The plating facility involved in this circuit board fabrication is the subject of this report. Mstsl EsGnvsrY _From Ernssss S!?l_utio_ns n their plating facility, Telex uses solutions which become contaminated or otherwise unusable, or which generate dilute metal-bearing rinse solutions. The quantities generated of these solutions varied from a continuous, low-concentration stream flowing at.5 gallons per minute, to a twice-a-week accumulation totaling 50 gallons. Telex wished to have options to off-site disposal for these waste streams. t was important that these options be inexpensive and simple to implement. MnTAP suggested the options listed for each process solution shown: Electroless copper plating solution - Chemical precipitation as copper hydroxide and reclaim - "Plate-out" of copper metal Palladium Catalyst - Precipitation of palladium metal from solution using aluminum and reclaim - Chemical precipitation as metal hydroxide and reclaim Tin/Lead Static Rinse - Electrolytic metal recovery - Precipitation of metal from solution using "cementation" reaction with aluminum Copper Etchant - Crystallization of metal from solution as copper sulfate Various Copper-Bearing Acidic Solutions - Precipitation of metal from solution using "Cementation" reaction with steel or aluminum

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3 P_rn_cess E_h_a!!g_es for waste Bsduc$io!! MnTAP also evaluated options for changes in equipment layo'ut and processing procedures which could reduce the amount of metals reaching the waste stream. Once again it was important that these dptions be inexpensive and simple to implement. The following suggestions werb presented to Telex. - nstall drip tank6 after tin/lead and acid copper process solutions to capture solution for direct recycle to the process tank - nstall drain boards between all process tanks to direct solution dripping from circuit boards toward the appropriate tank - Move tanks to allow for more efficient process flow, eliminating opportunities for drips to reach the floor - Decrease water flow to.5 gpm in most rinse tanks, adding air agitation to maintain rinsing efficiency Telex is now implementing many of these suggestions, and expects to save money previously spent for replacement process chemicals. off-site disposal, and excessive use of water and sewer. J Terry Foecke is completing a Bachelor of Science degree in Technical Communications, Fall Terry's background includes thirteen years of previous experience in the electroplating indus t ry.

4 PROCESS DESCRPTON The atmospheric evaporation process as applied to an electroplating process involves the inscallation of evaporators in close proximity to the electroplating or nickel plating baths Consideracion should be given to locacing che evaporator close Co a source of clean and dry air. A continuous flow of air which is humidified by the electroplating bath is drawn off and expelled to the atmosphere. Unsaturated air absorbs moisture from a wet surface. Therefore, as the relative humidity drops, the.evaporation rate increases. Head space or room is created in the plating tanks by taking advantage of the air's ability to absorb water while leaving i the valuable consticuents of the bath behind. The water evaporated is replaced by water from the rinse cycle. Figure illustrates the process sequence. The electroplating bath solution is pumped to the evaporator utilizing a magnetic drive March pump with a " suction and 314" discharge chrough the feed line to the two spray nozzles on cop and one spray nozzle in the middle front of the evaporator. Latent heat of vaporization occurs upon passing through the spray nozzles and packing while coming into contact with forced air from a Dayton blower. The! humidified air is expelled to the atmosphere through a 16", 20 gauge galvanized duct, with a 4" d rain for condensation. - - The bath which is noc evaporated returns to its original bath through a 1%'' 1 drain by gravity. 4

5 01. UATER -N- 40 CPH. tttf-eik CONMNSATON LNE TO RNSE. ATMSPHERC EVAPORATOR u FORCm AR ll A - WDRK FLOU AVERAGE FLOU RATE S CpH. - FEE0 LNE 0 1 RETURN RNSE13 RNSE12 FGURE 1 : OPERAT NG SEQUENCE FOR ATMOSPHERC EVAPORATOR SYSTEM

6 The replacement of evaporated water in the nickel bath is accomplished by pumping from the Rinse #. The amount of replacement is determined by the evaporation rate via a level control in the nickel bath. Simultaneously counterflow from Rinse #2 and Rinse 13 occurs as the level in Rinse # drops.! 1 As the level is dropping in Rinse # a'solenoid valve is opened allowing for dionized water to enter R use #3. Evaporation rates are variable and surrounding air, temperature of the so Conditions which favor evaporation are are determined by the ution and flow of air. hot air, dry air. hot solution and high air flow. Figure 2 shows the manufacturers average actual and theoretical rate of evaporation. Actual, according to the manufacturer are results reported by users of the systems. 6

7 e RATE OF EVAPORATON NCKEL PLATE LNE - LEGEND. THEORETCAL 1-1 ACTUAL v o m a== u o 30 > U c3 10 -lrm"rllr-*( l l l l l l Process Temperature Degrees Fahrenheit FGURE 2

8 TEST RESULTS AND ANALYSS 1 The test results clearly indicate that evaporative recovery is a feasible solution to closing the loop. All engineering technical data indicated the feasibility of this process as applied to an electroplating operation. TEST RESULTS t was determined in the pre-installation testing that an unacceptable conductivity occurred at 100 phos to obtain an 1 i acceptable product and finish. Also a flow rate of fresh water at 45 gallons per hour would stabilize automatic electroplating operation at the rinse water in an 000 pmhos. Testing following installation showed the conductivity varied fram pmhos in the third rinse tank. This was welt below the unacceptable range of pmhos. The total actual evaporation rate has averaged between gallons per hour. from the 500 and 750 gallon electroplating baths. Bath temperature ranges from 145OF - 150'F. This decrease in evaporation from the manufacturers actual is primarily due to climatic conditions surrounding the evaporators. 1! -i 20

9 j: :::...: COST ANALYSS As derived from the heat of vaporization 970 Btu per pound of water are required to change the state. Therefore, Btu per lb. x 8.34 gal. - 8,089.8 Btu per/gal. 8,090 Btu per gallon of evaporation are required. With the evaporation rate averaging between gallons par hour 485, Btu or therm per hour are used. nasmuch as this electroplating operation runs 24 hours per day16 days per week; therms are requiii annually to operate the system. The cost per therm of natural gas at chis facility is 47c per therm. Therefore energy costs at $17, , can be expected annually. #&4 SPhivm would continue to buildup at a rate of 3% due to anode/cathode efficiency and recovery. eliminating any future costs of nickel sulfate and nickel chloride. Table 2 shows breakdown and assessment of cost, payback period and annual cost: savings associated with this system ).... :.. '.... ' 21

10 TABLE 2 - COST AND PAYBACK ANALYSS 1. Plating chemicals - COST SAVNGS Nickel Chloride ANNUALLY 100% RECOVERY $ 9, Nickel Sulfate 22,0001/ $ % ANNUALLY l RECOVERY Boric Acid = $19, $ % ANNUALLY P RECOVERY = $ 3, Two (2) evaporator systems = $ Valves, switches, piping, Labor for installation,.duc twork for venting 3. Disposal Costs $ 5, Roll-off $ MO rental x-= 12 MO $ 3, Quarterly Transporta i n QUARTERLY 4 x-= YR $ 3, Landfill Costs = Labor to handle waste = $ 4, $ Maintenance on Evaporator - x- Hr 312 $20.00 DAY DAY BR (OH) $ 6,

11 ':~1~..;:,: Annual Water - 20 Gal to 60 Gal MN BR Sewer usage $ 7. Energy usage = $18,so 1.oo - COST SAVNGS $ 2, , $36, $60, st year projected savings... $24, Subsequent annual savings... $36, Projected?ayback Months Note: Annual savings does not include an undertetmined long-term liability savings. J 3 J :..... '... 23

12 CONCLUSONS F a ibility testing f the Atmosphe ic Evaporation system was successfully performed on the electroplating process from the lco Unican Corporation, Rocky Mount, North Carolina plant. n addition, analysis of the data from the tests provided the following conclusions regarding performance of the Atmoshperic Evaporation process. O Processing parameters (bath composition, temperature, climatic conditions, energy efficiencies for the Rocky Mount process demonstrated the feasibility of using Atmospheric Evaporation to process plating bath composition and effectively use the rinse water as recovery source, therefore closing-the-loop. La, 0 Seti-km buildup has been a problem in the evaporator and the problem has been resolved by operating the pump approximately 30 minutes every 24 hours without the blower. * Recovery of all salts. acid and brighteners normally disposed of, in addition to a generation of salts based on anode/cathode efficiency has occurred. Additionally a decrease of 50-80% in waste has occurred. 0 Conclusions about the continual buildup of contaminants to the plating bath cannot be derived from the available test data. However, the plating-industry is well aware 24

13 of various hydrogen p treatments involving carbon filtration, roxi.de, el ctrolytic dummy plating. which allows removal of most contaminants should they build to a detrimental level. 0 A off-line continuous dummy plate and creatment tank will be designed to decrease downtime associated with this process and any additional buildup of contaminants from the evaporator process. * Atmospheric Evaporation i's a cost-effective means. nitial testing indicates the potential for the Armospheric Evaporator to close-che-loop at the Rocky Mount plant. Based on the results of this feasibility test, adequate technical bases are available to design a system that is cost effective, efficient and act as a baseline for resolving problems associated with Atmospheric Evaporation in electroplating process. 25

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