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Gen Kleen 3650

Water based additive to add to Sulphuric acid Tank to efficiently and economically clean red and black copper oxides.


Product Description


Gen- Kleen 3650 is a concentrated additive added to Sulphuric acid tank used for the pickling of copper and copper alloys.

Extends the life of metalworking fluids
Easy to use
Proven efficacy against a broader range of bacteria and fungi

1. 3650 will remove cuprous (red) oxide and other oxides, which are left by sulfuric acid
2. Pickling used to remove, black cupric oxide scale.
3. 3650 eliminates pollution problems caused by the use of chromium compounds.
4. 3650 is compatible with both electrolytic and crystallization copper recovery processes.
5. Metal surfaces, pickled in 3650 have improved appearance, and will not stain during rinsing
6. With copper recovery, the pickling solution may be reused indefinitely. Only the amount lost due to drag -out needs to be replaced with 3650 and acid.

The use of 3650 introduces no foreign metals to the bath, thereby, greatly simplifying waste treatment and copper recovery. The principal by-products of the reaction are copper sulfate and water.

The pickling rate with 3650 depends only on the concentration of sulfuric acid and the pickling solution temperature. The build-up of copper does not affect the pickling rats, until the bath is saturated with copper ions.

Crystallization recovers copper as copper sulfate, the purity is dependent upon the quality of the sulfuric acid used and the alloys are pickled.

Crystallization is adaptable to continuous operation and the copper sulfate can be concentrated. This recovery method takes advantage of the decrease in copper sulfate solubility with decreasing temperatures. For any but small tanks, the use of external cooling (cold water coils) in the crystallizing vessel is necessary.

The use of a centrifugal filter on a continuous basis is suggested for large volume installations. Centrifugal filters produce a relatively dry salt.

Electrolytic recovery has the advantage of recovering copper as a metal and regenerating the acid in the process. Electrolytic recovery of copper from 3650 solutions is quite simple. Contact General Chemical for suggestions on electrolytic recovery methods specific to your plant.

In solution, various combinations of sulfuric acid concentration and temperature are possible, depending upon the amount of scale to be removed and the alloy to be picked. A typical Gen-Kleen 3650 bath is:

Gen-Kleen 3650      2to 4% by volume
Sulfuric Acid             6 to 12% by volume
Temperature           90 to 155°F. (32 to 46°C.)



Sequence of Additions : the sulfuric acid is slowly added to cold water, followed by the addition of Gen-Kleen 3650. Mix thoroughly and allow the bath to cool below 140°F. (60°C.)

Pickling Temperature

The Gen-Kleen 3650 pickling bath can be used at ambient temperatures to 120°F (49°C)(Do not exceed 140°F (60°C). The higher temperature gives faster pickling rates. The most commonly used temperature range is 90 – 110°F (32-41°C). For greater economy, let the pickling solution cool to ambient temperature when not in use for prolonged periods (8 hours or longer).

Immersion Time

The immersion time is dependent upon (1) the amount of scale to be removed, (2) the pickling solution temperature, (3) the alloy being pickled, and (4) the surface finish desired. As a rule, spray application requires less time than soaking. Over pickling usually results in a matte finish.

Suggested Process Sequences

1. Surfaces with Scale, Pickle directly in 3650 pickling bath.
2. Surfaces with Grease or Oil, and Scale Degrease and rinse, prior to pickling.

Bath Life

The 3650 solution will continue to pickle metal up to the saturation point with respect to copper sulfate. At this point, waste treatment or copper recovery should be employed

Treatment Methods

1. Simple Neutralization – for small operations, copper can be precipitated as a hydroxide with lime or as a carbonate with soda ash. This method is simple, but the copper recovery is in a form which has little value. This method is generally employed for waste treatment purposes only and is also useful for rinse water treatment.

2. Crystallization

3. Electrolysis

Pickling and Appearance:

A very finely divided white flocculent precipitate is generally found in operating the Gen-Kleen 3650 bath. The presence of this precipitate does not interfere with the operation of the bath or with copper recovery. The suspended precipitate has little tendency to stick on the work piece being pickled and is readily removed by rinsing.

If desired, the precipitates can be removed by filtration. Actual filtration data indicates that there is very little weight of material involved.


The most economical method of operating a pickling bath is to use a metering system for 3650 additions. This is particularly easy with pickling operations, which remove the same general type of scale and have a predictable workload. It is then possible to operate at a steady state concentration, with 3650 being added at the same rate as it is being consumed in pickling.

For batch systems, it is necessary to perform occasional, simple, chemical analysis to determine the 3650 concentration and to make the appropriate additions. Primarily the workload processed and the tank volume will determine the frequency with which this is required.

It is necessary to make some provision for temperature control; cooling will normally be required to control temperature rises caused by the introduction of hot metal, either from a hot pre-pickle or, in some cases, directly from an annealing operation. Cooling may also be required if large surface areas are to be pickled in relatively small solution volumes. This is primarily necessary to avoid temperature increases, which result in over pickling.

Prolonged operation at temperatures above 140°F will result in accelerated metal losses and will cause unnecessary costs.


For 3650 pickling tanks and other equipment to be used in contact
with the pickling solution itself, the following materials have been found suitable:

1. 300 Series Stainless Steels
3. Polyethylene
4. Polypropylene
5. Koroseal
6. Teflon


In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Get medical attention. Flush skin with water. Wash clothing before reuse. Refer to the appropriate Material Data Safety Sheet.

Store in original closed container. Do not tamper with vent. Keep bungs in and unobstructed. Keep out of sun and away from heat. Store in a clean, cool area. Do not add any other product to this container. Empty drum completely. Never use compressed air to empty. When empty, rinse thoroughly with clean water. Use plastic valves only.

Note: The information presented herein is our interpretation of certain test results and field experience to date. The information is not to be taken as warranty or representation for which we assume legal responsibility, nor as permission or recommendation to practice any patented invention without a license. It is offered solely for your consideration, investigation and verification.