How decamerone tannery waste

 

(57) Abstract:

The method refers to the leather industry and for decamerone tannery waste. Chrome shavings treated with an oxidizing aqueous solution containing NaOH and H2ABOUT2. Then carry out the extraction, washing with water, centrifuge, four-flushing with water to pH 7.0-7.5 and a final spin. The processing of subsequent batches of chrome shavings are on the spent oxidizing solution of the previous party, the concentration of NaOH and H202in which previously brought to the original, 5-7 times used the spent oxidizing solution containing CR6, filtered and mixed with the treated ash solution, pre-filtered, containing Na2S, acidified with H2SO4to restore SG6to IG3with the formation of chromium sulfate solution, which is separated from the precipitate and sent for recovery. The technical result of the invention is to reduce the duration of the process, refusal of expensive reagents, reducing the volume of wastewater. 2 C.p. f-crystals, 1 table.

The invention relates to the leather industry and can be used in the processing of the ia supplementary source of protein raw materials in the production of gelatin, mezdrovogo glue and protein hydrolysate.

There are various ways to decamerone waste leather chrome tanning.

The known method includes treatment of chrome shavings 3% solution of sodium hydroxide in the ratio of 1:10 for 3 hours for the swelling, rinse carefully chip from alkali running water, squeezing, extraction of water for 24 hours, extraction, processing 3% solution of sulfuric acid in the ratio of 1:10 for 24 hours, carefully pressing, extraction of water for 24 hours and the final spinning [1].

The known method, including leaching of waste water, treatment with a mixture of reagents that form coordination complexes with ions of trivalent chromium, washing with water, the processing of the oxidation mixture to switch IG3+in soluble form CR6+additional washing with water, distillation and deionization from Cr6+[2].

The known method, including leaching of waste water, acid treatment for 2 days with acid concentration of 2.5%, and the acid used solutions of phosphoric, oxalic, citric and other acids, additional processing of the oxidation mixture consisting of 2% sodium hydroxide solution (alcohol water to a content of chromium oxide in the waste of 0.4% [3].

The disadvantages of these methods are: long duration processes, the use of expensive reagents, large amounts of wastewater containing hexavalent chromium, which is 100 times more toxic than trivalent.

The technical result of the invention is to reduce the duration of the technological process, refusal of expensive reagents, reducing the amount of wastewater and the liquidation of the content of hexavalent chromium.

This technical result is achieved due to the fact that in the way decamerone tannery waste, mainly of chrome shavings, including its handling of oxidizing solution, centrifuge, wash with water, centrifuge, four-flushing water to a pH of 7-7,5, and the final spinning, characterized in that the processing of chrome shavings are in the oxidation solution composition, g/l:

NaOH - 8 - 10

H2ABOUT2- 2 - 2,5

Water up to 1 l,

the processing of subsequent batches of chrome shavings are on the spent oxidizing solution of the previous party, the concentration of caustic soda and hydrogen peroxide in which previously brought to the original.

Many times 5-7 times, used exhaust oxidize the solution, pre-filtered, containing Na2S=5-6 g/l), acidified with sulfuric acid for the recovery of hexavalent chromium to trivalent with the formation of chromium sulfate, which is separated from the precipitate and sent for recovery for further use in tanning processes.

Processing of chrome shavings in the oxidation solution is carried out at a temperature of 18-20oWith liquid ratio (LC) equal to 5, for 15-20 minutes periodic mixing: 0.5 to 1 minute, stirring, 1-2 minutes rest. Then the spent solution is poured into the vessel preparation and storage of oxidizing solution to edit and reuse.

Decamerone chips wring out, squeeze water are also sent to the capacity of the preparation and storage of oxidizing solution.

Wrung chips pour water with a temperature of 18-20oWith flat, equal to 5, and mix in periodic mode: 0.5 to 1 minute, stirring, 1-2 minutes rest for 10-15 minutes.

The washing water is separated, the part they are sent to adjust the spent oxidizing solution by volume, the other part is drained into the sewer.

The content of CR6+in waste VK, equal to 8, within 10-15 minutes of continuous stirring, with intermediate plums wash water, which contains IG6+in a decreasing concentration from 0.5 to 0.1 mg/l to pH decamerone chip 7,0-7,5 and residual CR6+equal 0,034-0,2%, and sent for further processing.

The processing of subsequent batches of chrome shavings are on the spent oxidizing solution of the previous party, the pre-adjusted volume of up to 5000 litres and structure to content, g/l:

NaOH - 8 - 10

H2ABOUT2- 2 - 2,5

Water to 1 liter

After 5-7-brief use of the spent oxidizing solution containing 3-3,6 g/l of hexavalent chromium ions, it is subjected to filtering, frame filter press, is mixed with the spent ash solution is pre-filtered with the content of NaS=5-6 g/l, at a ratio of 1: 1,4-1,6, acidified with sulfuric acid to recover SG6+to IG3+according to the following scheme:

2Na2SGAs4+3Na2S+8H2SO4-->Cr2(SO4)3+3S+5Na2SO4+8H2O

The solution containing the chromium sulfate is separated from the precipitate and sent for recovery for further use in dubil chips presented in the table.

Example 1. In the apparatus (drum pendant type, screw or mixer) load 1000 kg of chrome shavings, humidity 60%, of the capacity of the preparation and storage of oxidizing solution serves 5000 l of a solution with a temperature of 20oWith that composition, g/l: NaOH 8, H2ABOUT22, water to 1 l the Handset is put into rotation in periodic mode: rotation - 1 minute rest - 2 minutes.

The total processing time of 20 minutes.

After this time the spent solution is poured into the vessel preparation and storage of oxidizing solution for correcting and re-use.

Decamerone chips are sent to release equipment (entrance roller press, screw press, frame filter press, centrifuge, etc.), dewatering water is also poured into the vessel preparation and storage of oxidizing solution.

Wrung chips are loaded into the machine, pour 5000 l of water with a temperature of 18-20oC. the Apparatus is put into rotation in periodic mode: rotating - 0.5 minutes, rest 1 minute.

The total processing time of 15 minutes.

After a specified time part of the wash water is drained into the tank preparation and storage of oxidizing solution for S="ptx2">

Chips wring out, loaded into the machine, pour 8000 liters of water with a temperature of 18-20oC. the Apparatus is put into rotation and continuously rotate within 15 minutes. The washing water is drained into the sewer.

The washing process is repeated three more times to achieve a pH of wash water, respectively, and the chip, the values of 7.0-7.5 and a residual content of CR6+in the chips - 0,034-0,2%.

Decamerone and washed chips wring out and sent for further processing.

Example 2. In the device (same as example 1) load 10000 kg of chrome shavings, humidity 60%, of the capacity of the preparation and storage of oxidizing solution serves corrected exhaust oxidizing solution of example 1 (first use) with a temperature of 18oWith that composition, g/l: NaOH 10, H2ABOUT22.5, water to 1 l the Handset is put into rotation in periodic mode: rotating - 0.5 minutes, rest 1 minute.

The total processing time of 15 minutes.

After this time the spent solution is poured into the vessel preparation and storage of oxidizing solution for correcting and re-use.

Decamerone chips wring out analogously to example 1.

The total processing time of 10 minutes.

Next, the chips are treated analogously to example 1 and sent for further processing.

Example 3. The next batch of chrome shavings treated analogously to example 2, as the oxidizing solution using the corrected exhaust oxidizing solution of example 2 (second use).

Example 4. The next batch of chrome shavings treated analogously to example 2, as the oxidizing solution using the corrected exhaust oxidizing solution of example 3 (third use).

Example 5. The next batch of chrome shavings treated analogously to example 2, as the oxidizing solution using the corrected exhaust oxidizing solution of example 4 (fourth).

Example 6. The next batch of chrome shavings treated analogously to example 2, as the oxidizing solution using the corrected exhaust oxidizing solution of example 5 (fifth).

Example 7. The next batch of chrome shavings treated analogously to example 2, as oxidative RA is LASS="ptx2">

Example 8. The next batch of chrome shavings treated analogously to example 2, as the oxidizing solution using the corrected exhaust oxidizing solution of example 7 (seventh).

Example 9. The spent oxidizing solution of example 8 with the contents of CR6+= 3,63 g/l, which corresponds to the concentration of sodium chromate to 11.31 g/l, sucked frame filter press, is mixed with the spent ash solution, pre-filtered, with the content of Na2S=5-6 g/l, at a ratio of 1: 1.4 to 1.6 and add 28 kg of sulfuric acid (98%), for recovery of chromate sodium through the intermediate stage to sulfate chromium.

A solution containing sulphate of chromium in the amount of 13.7 g/l, separated from the sediment to the frame filter press and sent for recovery for further use in tanning processes.

Thus, by eliminating pre-rinse chrome shavings and acid treatment for 2 days; the application of available, inexpensive chemical materials; reduce the amount of effluent reuse the spent oxidizing solution containing toxic hexavalent chromium, reset the selected processes in leather production technical solution of the invention is achieved:

- the duration of the process is 75-110 minutes;

- for carrying out processes decamerone uses inexpensive, widely available chemicals: caustic soda, perhydrol, sulfuric acid;

- multiple (5-7 times) using the spent oxidizing solution with subsequent recovery of the contained hexavalent chromium to trivalent not only allows you to reduce the volume and toxicity of waste water, to return to the main production of chrome tanning agent in the form of recovered solution, but also to utilize not recuperated part of the waste ash solution.

Sources used

1. USSR author's certificate 1076062, MCI And 23 To 1/10, 1984

2. U.S. patent 4151161, 1979.

3. USSR author's certificate 193673, MKI With 14 3/32, 1967 (prototype).

1. How decamerone tannery waste, mainly of chrome shavings, including its handling of oxidizing solution, centrifuge, wash with water, centrifuge, four-flushing water to a pH of 7-7,5, and the final spinning, characterized in that the processing of chrome shavings are in the oxidation solution composition, g/l:

NaOH - 8 - 10

H2Othe chips are on the spent oxidizing solution of the previous party, the concentration of caustic soda and hydrogen peroxide in which previously brought to the original.

3. The method according to p. 1, characterized in that multiple times 5-7 times, used the spent oxidizing solution containing Cr6+= 3-3,6 g/l, filtered and mixed in a ratio of 1: 1,4-1,6 spent ash solution, pre-filtered, containing Na2S = 5-6 g/l), acidified with sulfuric acid for the recovery of hexavalent chromium to trivalent with the formation of chromium sulfate solution, which is separated from the precipitate and sent for recovery for further use in tanning processes.

 

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