CS227135B1 - Method of preparing tanning liquors from chromium-containing waste sludge - Google Patents

Method of preparing tanning liquors from chromium-containing waste sludge Download PDF

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CS227135B1
CS227135B1 CS326582A CS326582A CS227135B1 CS 227135 B1 CS227135 B1 CS 227135B1 CS 326582 A CS326582 A CS 326582A CS 326582 A CS326582 A CS 326582A CS 227135 B1 CS227135 B1 CS 227135B1
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Czechoslovakia
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chromium
sludge
solution
extraction stage
extraction
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CS326582A
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Czech (cs)
Slovak (sk)
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Jaroslav Ing Dedek
Josef Ing Csc Tkac
Antonin Ing Csc Galatik
Frantisek Ing Pecha
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Jaroslav Ing Dedek
Josef Ing Csc Tkac
Galatik Antonin
Frantisek Ing Pecha
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Priority to CS326582A priority Critical patent/CS227135B1/en
Publication of CS227135B1 publication Critical patent/CS227135B1/en

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Description

Vynález sa týká spósobu přípravy činiacich roztokov z odpadných kalov obsahujúcich chrom.The invention relates to a process for the preparation of tanning solutions from chromium-containing waste sludge.

V kožiarskej a kožušníckej výrobě sa využívaje roztoky trojmocného chrómu pri chromočinení. Tieto roztoky sú označované ako chromité brečky. Koncentrácia kysličníka chromičitého v brečke sa pohybuje v rozmedzí 30 až 150 g/l, bázicita brečky je obvykle 20 až 50 °Sch. Podl’a spósobu přípravy sa brečky rozdeTujú na kamencové, redukované a kombinované. Kamencové brečky sa pripravujú rozpúšťaním síranu chromitodraselného vo vodě, pričom požadovaná bázicita sa dosiahne přidáním bázifikačných činidiel. Při přípravě redukovanej brečky sa vychádza z dvojchromanu, ktorý sa rozpustí vo vodě, přidá sa potřebné množstvo· kyseliny sírovej a prevedie sa redukcia šestimocného chrómu na trojmocný přidáním redukovadla. Kombinovaná brečka sa připravuje zo síranu chromtodraselného a dvojchromanu sodného alebo draselného súčasne.In the leather and fur production, chromium (III) solutions are used in chromium tanning. These solutions are referred to as chromium slurries. The concentration of chromium trioxide in the sludge is in the range of 30 to 150 g / l, the sludge basicity is usually 20 to 50 ° Sch. According to the method of preparation, slices are divided into alum, reduced and combined. Alum slurries are prepared by dissolving chromium potassium sulfate in water, the desired basicity being achieved by the addition of basifying agents. The preparation of the reduced slurry starts from dichromate, which is dissolved in water, the required amount of sulfuric acid is added and the reduction of hexavalent chromium to trivalent is carried out by the addition of a reducing agent. The combined slurry is prepared from both potassium-potassium sulfate and sodium or potassium dichromate simultaneously.

V kožiarskej výrobě vznikajú často kaly s obsahom chrómu, a to například v odpadných vodách alebo pri spracovaní pri chromočinení, například pri výrobě doplňkového krmivá hydrolyzátů glutinu. Obsahujú obyčajne 5 - 15 % hmotnostných Cr20j na sušinu kalu. Tieto kaly sa priamo nevyužívájú ani nespracovávajú; výnimku tvoří iba alkalické zražanie hydroxik du chromitého z izolovaných odpadných roztokov pri chromoči- 2 .227 135 není, kedy sa získá hydroxid chromítý v dostatočnej čistotě, takže ho možno priamo přidávat do reakčnej zmesi při přípravě redukovanéj brečky. Tieto postupy sú známe pri takzvanéjrekuperácii odpadných činiacich kúpeTov pri chromočinení. Vo váěšine prípadov odpadajú kaly hydroxidu chromitého silno znečistěné, takže ich priame použitie při vaření brečiek nie je možné· Také kaly sa vozia na skládky alebo sa kanalizujú, čím prisjdevajú k zvyšovaniu obsahu chrómu v primárných kaloch v čistiarňach odpadových vod. Přítomnost chrómu sťažuje využitelnost čistiareriských kalov v polnohospodárstve, vzhladom k přísným hygienickým predpisom platným v ČSSR.In the leather industry, sludges containing chromium are often produced, for example in waste water or in the treatment of chromium tanning, for example in the production of supplementary feed of glutin hydrolyzates. They usually contain 5 - 15% by weight of Cr 2 O 3 per dry sludge. These sludges are not directly used or processed; the only exception is the alkaline precipitation of chromium (III) hydroxides from the isolated waste solutions in chromium-2 (227) 135, where chromium hydroxide is obtained in sufficient purity so that it can be directly added to the reaction mixture in the preparation of a reduced slurry. These processes are known in the so-called recovery of waste tanning baths in chrome tanning. In most cases, the slurries of chromium hydroxide are heavily contaminated, so that their direct use in boiling sludge is not possible. The presence of chromium makes it difficult to use sewage sludge in agriculture due to the strict hygiene regulations in force in Czechoslovakia.

Uvedené nevýhody v podstatnej miere odstraňuje spdsob přípravy činiacich roztokov z odpadných kalov obsahujúcich chrom, ktorého podstata spočívá v tom, že kaly sa extrahujú vodným roztokom obsahujúcim 1,5 až JO % hmotnostných kyseliny sírovej pri teplote 20 až 90 °C po dobu 5 až JO minút, potom sa extrahovaný roztok oddělí od nerozpustného zbytku kalu a získá sa kyslý roztok chromítých solí, ktorý sa ďalej upravuje až do koncentrácie chromitej soli JO až 150 g kysličníka chromitého na liter s bázicitou 20 až 50 °Sch.The above disadvantages are substantially eliminated by the process of preparing tanning solutions from chromium-containing waste sludge, which consists in extracting the sludge with an aqueous solution containing 1.5 to 10% by weight sulfuric acid at 20 to 90 ° C for 5 to 10%. minutes, then the extracted solution is separated from the insoluble residue of the sludge to give an acidic solution of chromium salts which is further treated to a chromium salt concentration of up to 150 g of chromium trioxide per liter with a basicity of 20 to 50 ° Sch.

Extrakcia je usporiadaná do trojstupňového protiprúdového systému, kde v prvom extrákčnom stupniprichádza do styku čerstvý chromí tý kal s kyslým roztokom získaným zmiešaním kyseliny sírovej a pracej vody oddelenej z druhého extrakčného stupňa, pričom táto pracia voda vznikne vypráním kalu odpadajúceho v 1. extrákčnom stupni pracou vodou získanou v treťom extrákčnom stupni, v ktorom kal odpadajúci v druhom extrakčnom stupni sa premyje vodou a odpadá ako odchrómovaný kal.The extraction is arranged in a three-stage countercurrent system, in which, in the first extraction stage, fresh chromium sludge comes into contact with the acidic solution obtained by mixing sulfuric acid and washing water separated from the second extraction stage. obtained in the third extraction stage, in which the sludge falling off in the second extraction stage is washed with water and discharged as a chromium sludge.

Na pripojenom obrázku je znázorněná schéma trojstupňovej protiprúdovej extrakcie chrómu z odpadných kalov podlá příkladu 2 oThe attached figure shows a diagram of a three-stage countercurrent extraction of chromium from waste sludge according to Example 2 o

-3 Příklad 1-3 Example 1

227 13S227 13S

Odpadný chromítý kal /sušina 37 %, popol 61 % na sušinu, obsah Cr^O^ 13 % na sušinu/ sa zriedi vodou v pomere 1:1a přidá sa 96 %-ná H^SO^ v. množstve 0,2θ kg na kg kalu. Zmes sa zahřeje do varu a nechá sa ochladit. Po ochladení sa oddělí extrahovaný roztok, ktorý má koncentráciu 2q g CrgO^/l a obsahuje 32 g voTnej HgSO^ /100 %-nej/ ná liter roztoku. Na 900 1 tohoto roztoku sa dávkuje 56 kg NagCr^O?^ HgO, súčasne sa zmec zahřeje na 90 °C a po rozpuštění dvojchrómanu sa prevedie jeho redukcia prídavkom sacharázy v množstve 11,2 kg. Po ochladení sa brečka doriedi do 1 000 1. Koncentrácia břečky je 55 g Cr20j/l, bázicita 4-5 °Sch.The waste chromium sludge (dry matter 37%, ash 61% dry matter, Cr? O? 13% dry matter) is diluted with water 1: 1 and 96% H 2 SO 4 is added. 0.2 kg / kg sludge. The mixture is heated to boiling and allowed to cool. After cooling, the extracted solution having a concentration of 2 g of CrgO4 / l was separated and contained 32 g of free HgSO4 / 100% liter solution. 900 kg of this solution is charged with 56 kg of NagCr2O2H2O, simultaneously heated to 90 [deg.] C. and after dissolution of the dichromate is reduced by addition of sucrose in an amount of 11.2 kg. After cooling, the slurry was diluted to 1000 L. The slurry concentration was 55 g Cr 20 0 / l, basicity 4-5 ° Sch.

Příklad 2Example 2

Získá sa extrahovaný roztok chromenu podl’a postupu na pripojenom obrázku. K odpadnému chromitého kalu /sušina 29 %, popol 53 % na sušinu, obsah Cr20^ 9,4 % na sušinu/ sa přidá 96 %-ná HgSO^ v množstve 0,15 kg na kg kalu a rovnaký objem roztoku po druhej separácii /1^/. Zmes sa zahřeje do varu.Po separácii roztoku R^ sa zostávajúci kal /Z2/ zriedi roztokom po tretej separácii /R^/. Z tejto zmesi sa pri druhej separácii oddělí roztok í^, zostávajúci kal /Z^/ sa zriedi vodou. Konečne po tretej separácii sa oddělí roztok Rj, pričom zostane vyextrahovaný kal Z^. Roztoky R> a R^ sa vracajú do predchádzajúcich stupňov extrakcie. Roztok R^ je výsledný extrahovaný roztok chrámu. Má koncentráciu 32 g Cr20-j/l. a obsahuje 37 g voTnej I^SO^ Αθθ %-nej/ na liter roztoku. Na 900 1 tohoto roztoku sa dávkuje’ 74,5 kg Na2Cr20^ · 2 H^O, súčasne sa zmes zahřeje na 90 °C a po rozpuštění dvojchromanu sa prevedie jeho postupná redukcia prídavkom sacharozy v množstve 15 kg. Po ochladení sa brečka doriedi na 1 000 litev. Koncentrácia chrámu je 67 g Cr20^/l, bázicita 45 °Sch.The extracted chromene solution is obtained as described in the attached figure. To the chromium waste sludge (dry matter 29%, ash 53% dry matter, Cr 2 O content ≥ 9.4% dry matter), 96% HgSO 4 is added in an amount of 0.15 kg per kg of sludge and an equal volume of solution for the second time separation (1). The mixture was heated to the separation varu.Po solution R, the remaining sludge / Z 2 / diluted solution of the third separation / R /. From this mixture the second solution is separated in a second separation, the remaining sludge (Z) is diluted with water. Finally, after the third separation, the solution R1 is separated, leaving the sludge Z ^ extracted. Solutions R1 and R2 are returned to the previous extraction steps. Solution R1 is the resulting extracted temple solution. It has a concentration of 32 g Cr 2 O / l. and it contains 37 g of free water per liter of solution. At 900 l of this solution, 74.5 kg of Na 2 Cr 2 O 2 · 2 H 2 O are metered in, simultaneously the mixture is heated to 90 ° C and after dissolution of dichromate is gradually reduced by adding sucrose in an amount of 15 kg. After cooling, the slurry was diluted to 1,000 liters. The concentration of the temple is 67 g Cr 2 O 4 / l, basicity 45 ° Sch.

- 4 Příklad 3- 4 Example 3

227 135227 135

Na 700 1 extrahovaného roztoku z příkladu 2 sa dávkuje 192 kg Na2Cr207 o 2 H20„ Po rozpuštění dvojchromanu sa přidá 164,5 kg 96 %-nej H2SO^. Zmes sa zahřeje na 90 °C a prevedie sa redukciou dvojchrómanu sacharozy v množstve 38>4 kg. Po ochladení sa brečka doriedi do 1 000 litorv. Koncentrácia chrómu v brečke je 150 g Cx^O^/l, bázicita 45 °Sch.To 700 l of the extracted solution of Example 2, 192 kg of Na 2 Cr 2 O 7 o 2 H 2 O are metered in. After dissolution of dichromate, 164.5 kg of 96% H 2 SO 4 are added. The mixture is heated to 90 ° C and carried out by reducing the sucrose dichromate in an amount of 38> 4 kg. After cooling, the slurry was diluted to 1000 liters. The concentration of chromium in the slurry was 150 g of Cx ^O ^ / l, basicity 45 ° Sch.

Příklad 4Example 4

K extrahovanému roztoku z příkladu 2 sa přidá síran chromitodraselný v množstve 0,6 kg na liter roztoku a rozvaří sa priamou parou. Takto vzniknutý roztok sa bazifikuje prídavkom pevného Na^CO^ až do dosiahnutia bázicity 35 °Sch. Koncentrácia brečky sa upraví na 100 g Cr20^/lo To the extracted solution of Example 2, 0.6 Kg of potassium sulfate was added per liter of solution and boiled by direct steam. The solution thus obtained is basified by the addition of solid Na 2 CO 3 until the basicity is 35 ° Sch. The concentration of the slurry is adjusted to 100 g of Cr 2 0 ^ / l o

Claims (2)

1. Spósob přípravy činiacich roztokov z odpadných kalov obsahu júcich chróm vyznačujúci sa tým, že kaly sa extrahujú vodným roztokom obsahujúcim 1,5 až 30 % hmotnostných kyseliny sirovej pri teplote 20 až 90 °C po dobu 5 až JO minút, potom sa extrahovaný roztok oddělí od nerozpustného zbytku kalu a získá sa kyslý roztok chromitých solí, ktorý sa ďalej upravuje až do koncentráoie chromitej soli 30 až 150 g kysličníka chromitého na liter s bazicitou 20 až 50 °SchoProcess for preparing tanning solutions from chromium-containing waste sludges, characterized in that the sludges are extracted with an aqueous solution containing 1.5 to 30% by weight of sulfuric acid at a temperature of 20 to 90 ° C for 5 to 10 minutes, then the extracted solution separating from the insoluble residue of the sludge to give an acidic solution of chromium salts which is further treated to a chromium salt concentration of 30 to 150 g chromium trioxide per liter with a basicity of 20 to 50 ° Scho 2 o Spósob podl’a, bodu 1 vyznačujúci sa tým, že extrakcia je usporiadaná do trojstupňového protiprúdového systému, kde ✓2 o The method according to clause 1, characterized in that the extraction is arranged in a three-stage countercurrent system where ✓ v prvom extrakčnom stupni prichadza do styku čerstvý chromitý kal s kyslým roztokom získaným zmieáaním kyseliny sírovej a pracej vody oddelenej z druhého extrakčného stupňa, pričom tato pracia voda vznikne vypráním kalu odpadajúceho v prvom extrakčnom stupni, pracou vodou, získanou v teťom extrakčnom stupni, v ktorom kal, odpadajúci v druhom extrakčnom stupni, sa premyje vodou a odpadá ako odchrómovaný kal.in a first extraction stage, fresh chromium sludge is contacted with an acidic solution obtained by mixing sulfuric acid and wash water separated from the second extraction stage, wherein the wash water is produced by washing the sludge falling off in the first extraction stage with wash water obtained in the same extraction stage; the sludge falling off in the second extraction stage is washed with water and is removed as a chromium-plated sludge.
CS326582A 1982-05-06 1982-05-06 Method of preparing tanning liquors from chromium-containing waste sludge CS227135B1 (en)

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