Metal finishing Q&As since 1989

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New technology for treating chrome plating wastewater

 

I have my own company and I am making a survey - business plan - regarding the market of chromium coverings in USA . That is why I need a lot of data referring to the above mentioned subject in order to complete the survey and submit it to the approval of the Romanian - American Enterprise Fund from Romania. The business plan will be checked by Arthur Andersen too and by the Romanian Bank for Development - Group Societe Generale.

I found out about www.finishing.com 8 months ago and I think that it can offer complete answers for those who work in this field (in comparison to Europe where you cannot find such information).

And now I will explain to you, in detail, what is the subject of my study and what exactly I need from you: two Romanian chemical engineers patented a completely ecological process for the retrieval of metal oxides after the neutralization of the concentrated used water chroming solution from the non-ferrous and ferrous materials. I would like you to read annex number one where the process is presented in short. As you can see from the annex , after using the process there results 75 - 78 % percent chromium green oxides and 22 - 25 % percent metal oxides. Taking into account the fact that this process is a completely ecological one, it is cheap and it can be used in a field in which the pollution regulations are very strict, I am convinced that it can and will have a great impact on the market of chromium coverings. In order to present a credible case study I will need the prices for the following products which, I would kindly ask you to send to me:

No. Name of the products Measuring unit Price
1. Green chromium oxide - pigment USD / kg
2. Electric energy USD / MW
3. Ca ( OH )2 USD / to
4. NH 3 - industrial gas cylinder USD / to
5. Zn ( CN )2 USD / to
6. Na Cl O USD / to
7. Na Fe ( CN)3 USD / to
8. Na C N USD / to

I only have, at the moment, the following data for the USA:

- the annual quantity of concentrated waste waters from the chroming baths 70.000.000 gallons / year = 265. 300 m3 ~ 265. 300 to
- the price of chromium green oxide - pigment ( purity over 99 % ) 5 - 7 USD / kg
- electrical energy price 38 - 45 USD / MW / h
- the price for collecting the concentrated used water chroming solution from the waste producers 370 USD / to

As far as it is possible on your behalf and if you are interested in the above mentioned problem I would like you to give me some suggestions in order to achieve a very good business plan.

I am looking froward to your answer and wish me luck.

ANEXA 1

METHOD AND INSTALLATION OF RETRIEVING OF METALS FROM USED CHROMING SOLUTIONS

The invention concerns a method and an installation of retrieve metals after the neutralizations of the used water chroming solution, proceeded from the chroming bath of pieces made from ferrous or non-ferrous materials. In the field of protection covering, a place of its own is occupied by the functional and protecting depositions - decorative by hard chroming. During the anode attack of the pieces to be chromed into the solution are passing metallic ions from the superficial layer that can be iron, copper, zinc, nickel and others. Also in this solution there are forming ions of Cr+3 by reduction of Cr+6 at the cathode. The iron and Cr+3 in thin concentrations improve the covering capacity of chroming solution. It has been proved that the sum Fe + Cr+3 must not be over 20 g/l, value over the efficiency of the processes is decreasing and the chroming solution is considered worn out. There are methods of neutralization and retrieval of metals from a solution of chroming that is used, methods consisting either in treatment with iron salts or calcium salts or treatment with reactive of precipitation of Cr+6 as insoluble chromate, using barium alts or lead salt, or the separation of Cr+6 from the other metals with the help of the ion changer or by Electro-dialysis. The drawbacks of these methods consist in the neutralization of the solution of chroming used in order to purify the residual waters to be eliminated. In this way, result abundant muss that imply either adequate storage or use of expansive toxic reactive, requesting precise dozing in order to avoid any excess. The technical issue that our invention is solving consists in the retrieval, from the water used chroming solutions, of both the active metallic element that is Cr+6 and the impure metallic elements. A single reagent is used and the neutralization container can be even the chroming bath and in the final of the method, the pH is of 5,5 - 6,0.

The method and the installation, according to the invention, have the following advantage:
- Does not have negative environmental impact over:
 Water - because does not discharge any solution, because the product resulted following the method are solid
 Atmosphere - the volatile products are not toxic.
 Soil - all resulted products are not toxic and can be used again.
- Does not require space for waste storage because there are not, practically no waste.
- Doesn't present toxic danger to the operator
- Permits the treatment separate of chroming bath, without requiring prior analyze of the solution
- Allow the separation of the Cr+6 from the solution, from the impure metallic elements
- Allows the retrieval of metallic impure elements as insolvable products non-toxic and reuse possible.
- The technological method is relatively simple and not expansive.

THE SCHEME OF THE TECHNOLOGICAL PROCESS

Reactive → Reaction tanks (chroming bath) → Press filter →
Evaporation → Calcination → Mill with balls
↓
↓
Solution Cr+6, metallic oxides, Chrome oxides, Insoluble chromate

Examples: Solution density CrO3 gr./l Cr2O3 gr./l theoretic Cr2O3 gr./l practice

1,035 50 38 30
1,070 100 75 60
1,105 150 110 85
1,140 200 150 120
1,175 250 190 150
1,210 300 225 180
1,245 350 260 200

Alexandru COVACIU
RomIntel SA - ROMANIA

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I don't want anyone to think that a good business plan is not worth pursuing, but all of the items in your list are pretty inexpensive if you could solve the waste treatment problem of hexchrome.

I say the best plan would be to come over here with a working prototype that could handle 100 liters per minute of wastewater from a chromium plating plant (the parameters of this wastestream is what you really need to have well documented), set it up in a plating shop, divert 100 l/m of the wastewater to your unit and see what happens.

  
Tom Pullizzi
Falls Township, Pennsylvania