EP0092261A1 - Process and apparatus for the recovery of silver from films and fixing baths - Google Patents

Abstract

So-called incineration units for the recovery of silver from films are known. These pollute the environment and require expensive filter installations. The present process and apparatus for carrying out the process avoid these disadvantages. It requires only small funding and avoids expensive filter installations. The film is comminuted in a mill and then passes into stripping tanks with an enzyme-containing solution. After completion of the stripping step, the solution including film passes into a washing drum, in which the film is washed out. The solution separated from the film flows into a receiver tank underneath the washing drum and from there into intermediate storage tanks with stirrers. The solution then passes into a centrifuge, and the deposited solid is taken from there to a drying cabinet. After the end of drying, the material is ignited in a special furnace and then, with addition of a melting agent, melted in a melting furnace and subsequently cast to give ingots. The process takes place in the items of apparatus in the following order: mill, stripping tank, washing drum, intermediate storage tank, centrifuge, drying cabinet, igniting furnace, melting furnace. A particularly advantageous factor of the plant with regard to the environment is that the stripping tanks are heated by means of the stack exit air, the entire length of the furnace tube being wound with a water-filled copper line which leads to the stripping tanks and back again to the furnace tube, with an interposed circulation pump.

Description

The invention relates to a method and apparatus for recovering silver from films and fixers = baths.

Methods are known, so-called combustion plants for the recovery of silver. They are environmentally harmful and therefore require expensive filter systems.

The method according to the invention and the device for carrying it out avoids the disadvantages of known methods. It can be used for all commercially available film materials such as X-ray films, reprofilms, industrial films etc.

The advantages of the process lie in the comparatively low financial outlay (no expensive filter systems = as in incineration plants), the low operating costs, the high throughput, and the fact that the waste material (film) accumulates again can be sold for other uses.

The procedure in the apparatus is as follows. The film is chopped up in a mill (shredded, then it is placed in a detachment container in which there is an enzyme-containing solution (water and bacterial bread = ase N). Depending on the type of enzyme, this solution has a temperature of approx. 30-60 degrees C. After completion of the The enzyme solution, including the film, is pumped into a washing drum, where the film is washed out, the washed film remains in the washing drum, and the silver-containing solution separated from the film goes into a collecting container under the washing drum brought into intermediate storage containers by means of a pump. Motor-driven agitators are provided in these containers, which keep this solution in motion. The solution now passes into a centrifuge, whereby a suitable pump is provided for the loading. After centrifugation has ended, the Now, the silver-containing, puncture-proof mass is fed into a drying cupboard The material is melted in the melting furnace with the addition of a suitable melt. Then it is poured into bars.

• Fig.1 eine Ansicht der Mühle,
• Fig.2 die Ablösebehälter entsprechender Zahl,
• Fig.3 eine Ansicht der Pumpe 1,
• Fig.4 eine Ansicht der Waschtrommel,,
• Fig.5 eine Ansicht der Pumpe 2,
• Fig.6 die Zwischenlagerbehälter,
• Fig.7 eine Ansicht der Zentrifuge,
• Fig.8 eine Ansicht des Trockenschrankes,
• Fig.9 eine Ansicht des Veraschungsofens,
• Fig.10 den Schmelzofen,
• Fig.11 die geformten Silberbarren auf einem Tisch.

The drawing illustrates the device in the order of its application. Show it:

• 1 is a view of the mill,
• 2 shows the number of detachment containers,
• 3 is a view of the pump 1,
• 4 is a view of the washing drum ,,
• 5 is a view of the pump 2,
• 6 the intermediate storage containers,
• 7 is a view of the centrifuge,
• 8 is a view of the drying cabinet,
• 9 is a view of the ashing furnace,
• 10 the melting furnace,
• Fig.11 the shaped silver bars on a table.

The film is brought into the mill Fig. 1 and crushed therein. Then it comes into the detachment container Fig. 2, in which there is an enzyme-containing solution (water and bacterial bread asfi N. Depending on the type of enzyme, the solution has a temperature of 30-60 degrees C. In the detachment containers Fig. 2 there are motor-driven stirrers = If the detachment process is supported (approx. 2-3 hours) depending on the temperature, the enzyme solution including the film is pumped into the washing drum with the pump 1 Fig.3 Fig. 4. The water is washed out by adding water to the drum (spray nozzle) and rotating the drum; the washed film remains in the drum. Below the washing drum Fig. 4 there is a collecting container in which Now there is the silver-containing solution separated from the film This solution is again brought into intermediate storage container Fig. 6 with a pump 2 Fig. 5. In these containers there are motor-driven agitators which move this solution hold. This ensures a uniform penetration of the liquid and better sedimentation when flocculants are added. The silver = containing solution reaches the centrifuge Fig. 7 from the containers Fig. 6. In order to achieve the required inlet pressure, the intermediate storage containers are slightly higher than the centrifuge on a drip pan. The centrifuge is appropriately fed with a suitable pump.

At the end of the centrifugation there is a puncture-resistant mass which is fed to the drying cabinet Fig. 8.

After drying, the material is put into an ashing furnace Fig. 9. After ashing, the material is melted in the melting furnace Fig. 10 with the addition of a suitable melting agent. Then it is poured into bars (Fig. 11 with table).

The washed with this process Footage can be sold again for processing. One kilo of the washed film material has a higher calorific value than 1. liter of heating oil.

The chimney exhaust air is used for heating the detachment container Fig. A copper pipe is wound and insulated around the entire length of the stovepipe. This copper line is led to the detachment containers and then back to the stovepipe. The line is filled with water and a circulating pump is connected. This means that there is a sufficient heating circuit. This is an economical and effective heating of the detachment containers, since the drying cabinet Fig. 8 is constantly in operation during production.

Processing fixing baths:

Fixing baths can also be processed with this system. The fixer is placed in the intermediate storage tank Fig.6 and a suitable flocculant is added. Then the same processing as the silver-containing solution when recovering from film material. Sequence: detachment container, intermediate storage container, washing drum, drying cabinet, ashing, heating of the detachment container.

• ca. 0,2 g/kg.

Remaining silver content of the processed footage:

• approx. 0.2 g / kg.

Claims (6)

1.Procedure for the recovery of silver from films and fixing baths, characterized in that the film is crushed in a mill and then gets into detachment containers, in which there is an enzyme-containing solution (water and bacterial breadase N), with motor-driven agitators the film keep moving, after which the enzyme solution including film is pumped into the intended washing drum, in which, with the addition of water through the spray nozzle and rotation of the drum, the film is washed out, which then remains in the drum, while that of the film separate silver-containing solution is collected from a collecting container under the drum and by means of a pump into intermediate container, where it is kept in motion by means of motor-driven agitators, in order to ensure uniform penetration of the liquid and better sedimentation if necessary To achieve addition of flocculants; From the intermediate storage containers, the solution is pumped into the centrifuge provided and from there into the drying cabinet and after drying in the ashing furnace and after ashing, the material is melted in the melting furnace with the addition of a suitable lubricant and then into ingots poured. 2.Device for carrying out the method according to claim 1, characterized in that it is arranged and loaded in the sequence as below, Consisting of a comminution mill (Fig. 1), different separation containers (Fig. 2), a pump 1 (Fig. 3), a washing drum (Fig. 4), a pump 2 (Fig. 5), various intermediate storage containers (Fig .6), a centrifuge (Fig.7) together with a pump, a drying cabinet (Fig.8), an ashing device (Fig.9) and a melting furnace (Fig.10). 3.Device according to claim 2, characterized in that the detachment container (Fig.2) are provided with agitators which keep the film in motion. 4.Device according to claims 2 and 3, characterized in that the washing drum (Fig.4) is provided on the underside = with a receptacle for receiving the silver drum-containing solution leaving the washing drum. 5. Device according to claims to 4, characterized in that the intermediate storage containers (Fig.6) are provided with motor-driven agitators to keep the solution in motion. 6.Device according to claims 2 to 5, characterized = indicates that the detachment container (Fig.2) are provided with a heater, wherein the chimney exhaust air is used, such that around the entire length of the stovepipe = there is a copper pipe and is insulated, which is leading to the detachment containers and then back to the stovepipe, and that a circulating pump is connected to achieve a heating circuit of the water-filled pipe.

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