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Increasing the speed of cyanide zinc plating

Hi all.
I own a cyanide zinc plating shop where I plate perforated sheets. the sheets are of various sizes. right now I operate on 5 rectifiers and 10 tanks. each rectifier is 12v 500A and 2 single cathode line tanks connected to them are 8 ft in length (800 ltr). the bath concentration is 14 ZINC, 25 CYANIDE and 30 CAUSTIC. each tank has 8 anode plates 1ft height and 1/2 ft wide. now presently I plate around 14 Sq ft on 2 tanks per cycle. each cycle is of at least 5 mins. hence I can get around 3 microns thickness.
My query is of reducing the timing for plating so I can increase my production. please let me know the various steps and changes I can make for reducing the timing. if so how much can it be reduced.
Thank you.

Nikhil V lombar
electroplaters - India
2006

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Faraday's Law tells us that the thickness of the deposit is proportional to amperage multiplied by time, Nikhil. So the way to get the same thickness in less time is to increase the amperage. Of course, this can lead to burning, and if I understood your numbers, it probably will.

Still, 3 microns is minimal plating, and 5 minutes is minimal plating time. If I were designing a product I do not think I would specify so little thickness unless there were quite special circumstances. Are you really sure that you must reduce the plating time for your services to be viable? Maybe economics can be improved by switching away from cyanide?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2006

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2006

Hi Nikhil,
I am back on finishing.com after a break.
Whatever you get is technically right as Ted rightly said.
But to improve on the finish and economise the process you may have to do a lot; such as good house keeping,having more anode in the tank and better go for a good capacity filter unit as you have 10 tanks.
Regards

T.K. Mohan
plating process supplier - Mumbai, India

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2006

Hello Nikhil,

To obtain plating in shorter time , higher current is required. To pass higher current with caustic at 30 gpl without burning at HCD will be miraculous. You need maintain the solution which should read. Caustic 60 to 75 gpl while the metal at 14 is fine and cyanide can be taken to 30 gpl..

Which brings us to Alkaline Cyanide free zinc.

Did you know that Alkaline zinc works at 78 percent efficiency while a new Medium cyanide bath works at 65 percent efficiency. Your solutions were started while you were much younger and carbonate build in the intervening period may well reduce that 65% to a possible 55% or lower efficiency. Which means that MSEB is paid by you for 45% solution inefficiency.

Are you really serious Mr Nikhil about saving money.?
I suggest you start with a close look at the leakage of profit and plug that electricity underutilisation loss first.

Here is a rough calculation of ONE rectifier of yours 500 amps 12 volts rated.attached to 2 tanks. Lets assume you plate 12 Hours a day.Right ? and draw 450 amps .Right.

This here below is only an example for you.

Cyanide zinc: 450 amps x 10 volts divide by 1000 x 12 Hrs x 1.25 power factor for conversion loss. x 26 days a month x 12 months x Rs 4.5 per unit electricity. = Rs 25272 .00 per month. Electricity Cost of running two tanks.

By Paying Rs 25272 you deposit at an assumed 55 percent cyanide zinc efficiency ,approximately 1130 kilos of zinc in 2 tanks / per rectifier running at 450 amps for 12 Hrs for 26 days for 12 months. Got that ?

Which works out to Rs 22.36 as the electricity cost factor of depositing 1 kilo zinc out of your cyanide baths.

If you want speed Nikhil, look at Alkaline zinc.

The same two tanks drawing the same 450 amps on Alkaline Cyanide free zinc shall work as follows.

450 amps x 3.5 volts divide by 1000 x 12 Hrs x 1.25 power factor for conversion loss. x 26 days a month x 12 months x Rs 4.5 per unit electricity. = Rs 7371.00 per year Electricity cost of running two tanks.

Zinc Deposited. 1603 kilos a year.

Which gives us an electricity cost of Rs 4.6 per kilo of zinc deposited.

Now come to timings.

With the increase in plating efficiency you have two choices.

Allow current to remain constant and speed up production. If this is your choice, then you can reduce timings by anything from 37 to 40 percent.
(Of course the question is, can your manual plant workers move that fast to load and unload ? )

Your second choice might be to reduce current, to say 400 amps and plate 20 - 25 percent faster . This choice allows workers keep up with solution speed.

Think about this Mr Nikhil.

Meanwhile add the cost of a 1 HP filter for 12 Hours and one anodic cleaning tank to the electricity cost of depositing zinc. because you need a filter and an anodic cleaning tank for running alkaline zinc....And lastly, if you ever consider wanting to use Alkaline zinc, consult anyone in your town that runs alkaline zinc and has experience or ask the plating vendor that sells and services that Alkaline zinc account.. Someone like you should first get the right guidance before venturing into a new Technology.

Incidentally Pune has a number of alkaline Zinc baths at Job Platers too....

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016