Wyniki wyszukiwania - BazTech

1

Quick-traffic slurry surfacing mix with orthophosphoric acid

Sidun Iurii, Vollis Oleksiy, Hidei Volodymyr, Bidos Volodymyr

Production Engineering Archives

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2021

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Vol. 27, Iss. 3

191--195

EN

Bitumen emulsions for slurry surfacing mix technology using oxidized bitumen and hydrochloric and orthophosphoric acids on laboratory DenimoTech bitumen-emulsion plant are made in the work. Methylene blue adsorption index of granite aggregate for use in slurry surfacing mix was investigated. Comparatively mix time and cohesion strength build-up of selected compositions slurry surfacing mix with hydrochloric and orthophosphoric acids depending on the variable content of bitumen emulsion. The advantage of using orthophosphoric acid in slurry surfacing mix according to the cohesion strength build-up criterion has been proved. The importance of correct distribution of bitumen drops in the emulsion was confirmed using a sedimentograph Mastersizer 2000. Two emulsions of the same component composition were compared, which differed in particle size. It has been established that it is not possible to design a slurry surfacing mix using the mix time criterion with the help of coarse bitumen emulsion.

2

The effect of silica fume and zeolites on the leaching of ions from the cement matrix in environments of varying pH

Estokova Adriana, Sicakova Alena, Kovalcikova Martina

Ochrona przed Korozją

|

2020

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nr 11

358--363

EN

Concrete is a versatile construction material that can be used in a wide range of service and environmental conditions. Sustainable concrete is characterized by two basic features. It should withstand those conditions that can impact its service life (and should be identified during design and addressed in project specifications) as well as it contains some alternative raw materials in its composition. The paper aims at a simultaneous study of both chemical and engineering properties of concretes after an acidic exposure. For this purpose, a specific experimental program was set and executed, with the aim of using the proper size of samples for individual testing methods. Two kinds of additions (silica fume and zeolite) were used as concrete components. Two aspects of the impact of concrete´s composition were investigated: the impact on chemical behaviour (leaching the main concrete components) and the impact on physical-mechanical properties (density, water absorption capacity, flexural and compressive strength). Findings revealed that the best resistivity against HCl attack has been proven for the samples with silica fume addition only. The physico-mechanical performance of large-sized concrete´s and the results of leaching of small-sized concrete´s samples exposed to hydrochloric acid correlated well. The comparison of chemical and physical-mechanical performance of samples points to the necessity of complex evaluation of concrete durability.

PL

Beton jest wszechstronnym materiałem budowlanym, który można stosować w różnych środowiskach. „Zrównoważony” beton charakteryzuje się dwiema podstawowymi cechami: powinien wytrzymać warunki, które mogą wpłynąć na jego trwałość (i powinny zostać zidentyfikowane podczas projektowania i uwzględnione w specyfikacjach projektu), a także zawiera w swoim składzie pewne alternatywne surowce. W celu jednoczesnego badania właściwości chemicznych i inżynieryjnych betonu po ekspozycji w środowisku kwaśnym opracowano i uruchomiono specjalny program eksperymentalny, mający na celu zastosowanie odpowiedniej wielkości próbek dla poszczególnych metod testowania. W betonie zastosowano dwa rodzaje dodatków – krzemionkę płomieniową i zeolit. Przebadano wpływ dodatków na właściwości chemiczne (ługowanie głównych składników betonu) oraz na właściwości fizyko- -mechaniczne (gęstość, zdolność absorpcji wody, wytrzymałość na zginanie i ściskanie). Badania wykazały, że najlepszą odpornością na atak HCl charakteryzują się próbki z dodatkiem krzemionki płomieniowej. Uzyskano dobrą korelację właściwości fizyko-mechanicznych dla dużych i małych próbek betonu narażonych na działanie kwasu solnego. Porównaniem właściwości chemicznych i fizyko-mechanicznych próbek wskazuje na konieczność kompleksowej oceny trwałości betonu.

3

Acids in bitumen emulsions

Solodkyy S., Sidun I., Vollis O.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2018

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z. 65, nr 3

83--90

EN

In the article there is proved the possibility of using ortho-phosphoric acid with special emulsifiers instead of hydrochloric acid - for the production of road cationic slow-setting bitumen emulsions. There is ascertained the difference between used for bitumen emulsions distilled binder (Nybit E85 bitumen), produced from heavy crude oil, and oxidized bitumens (grade 70/100 bitumen produced by JSC Mozyr Refinery and grade BND 60/90 bitumen of JSC UkrTatNafta), produced from light crude oil. The difference is analyzed between physical-mechanical indices of distilled and oxidized bitumens. Eight bitumen emulsion formulations were developed based on usage hydrochloric acid, three bitumens and three emulsifiers (Redicote E-11, Redicote 404 and Redicote E-4875), as well as four formulations based on usage of ortho-phosphoric acid, two bitumens and two emulsifiers (Redicote EM44 and Redicote C-320). There was investigated the influence of hydrochloric and ortho-phosphoric acids upon the physical-technical indices of road cationic slow-setting bitumen emulsions and the difference was ascertained between the indices of bitumen emulsions based on distilled and oxidized bitumens. Bitumen emulsion formulations were developed based on usage of ortho-phosphoric acid and special emulsifiers for the class of cationic slow-setting emulsions for slurry seal and microsurfacing mixtures.

4

Przegląd badań elektrodialitycznego odzysku kwasu chlorowodorowego i skoncentrowanego strumienia jonów metali z roztworów odpadowych

Wolska M., Mrozowski J.

Rudy i Metale Nieżelazne Recykling

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2017

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R. 62, nr 3

19--24

PL

Problem zagospodarowania odpadowych roztworów kwasów mineralnych oraz odzysku metali, budzi coraz większe zainteresowanie technologiczne. W artykule dokonano przeglądu procesów elektrodialitycznego odzysku kwasu chlorowodorowego oraz koncentratu metali. Przedstawiono przykłady aplikacji procesów membranowych: elektrodializy oraz złożonych układów technologicznych typu elektrodializa i wymiana jonowa, elektrodializa i dializa dyfuzyjna w instalacjach recyklingu kwasu chlorowodorowego. Przykłady zostały omówione zarówno pod kątem technologicznym, jak i ekonomicznym.

EN

TThe problem of waste management solutions of minerał acids and metal recovery is a growing interest in the technology. In this paper, a review of processes electrodialytic recovery of hydrochloric acid and concentrated metals was presented. The examples of the application of membranę pro-cesses, ie. electrodialysis and complex technological systems such electrodialysis and ion exchange, electrodialysis and diffusion dialysis in recycling installations of hydrochloric acid was presented. The examples was discussed both in terms of technological and economic.

5

Największy w kraju zbiornik kwasu solnego

Kołek Z., Pociżnicki P., Lewandowski L.

Dozór Techniczny

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2017

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z. 1

8--11

PL

Artykuł dotyczy projektowania, wytwarzania, odbiorów technicznych, transportu i montażu największego w Polsce zbiornika z kompozytu poliestrowo-szklanego, o średnicy 12 m i pojemności całkowitej 1150 m3 do magazynowania stężonego kwasu solnego.

6

Kinetic study of zinc leaching from sal-ammoniac flux in acidic media

Smincakova E., Trpcevska J., Piroskova J., Blaskova K.

Rudy i Metale Nieżelazne Recykling

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2016

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R. 61, nr 1

31--36

EN

This paper presents the results of the laboratory investigation of acid leaching of sal-ammoniac flux. Sal-ammoniac is waste product originated during wet hot dip galvanizing process having about 40 % of zinc. Zinc is the most abundant element in the sal-ammoniac flux and in the supplied sample was occurred in the form of following phases: Zn5(OH)8Cl2 H2O in amount of 70.83 %, (NH4)2(ZnCl4) in amount of 24.02 % and ZnCl2(NH3)2 in amount of 5.5 %. Leaching test of sal-ammoniac flux in distilled water and aqueous solution of hydrochloric acid has been carried out kinetically. The experimental parameters of HCl concentration, leaching time and temperature were varied. The results obtained are as follows: The apparent activation energy of leaching reaction by hydrochloric acid solution was Ea = 6.28 kJ mol-1. The apparent order of reaction n = 0.33 was estimated.

PL

W artykule przedstawiono wyniki badań laboratoryjnych kwaśnego ługowania odpadowego salmiaku. Salmiak ten jest produktem powstającym podczas gorącej zanurzeniowej galwanizacji zawierający ok. 40 % mas. cynku. Cynk jest pierwiastkiem występującym w największej ilości, dostarczona (badana) próbka zawierała następujące fazy: Zn5(OH)8Cl2 H2O — 70,83 %, (NH4)2(ZnCl4) — 24,02 % i ZnCl2(NH3)2 — 5,5 %. Testy ługowania prowadzono w wodzie destylowanej i w wodnych roztworach kwasu solnego. W testach zmiennymi parametrami były: stężenie HCl, czas i temperatura ługowania. Uzyskano następujące wyniki: pozorna energia aktywacji ługowania roztworem kwasu solnego Ea = 6,28 kJ mol-1, pozorny rząd reakcji n = 0,33.

7

Chemical treatment of kaolin. Case study of kaolin from the Tamazert– Jijel mine

Chouafa M., Idres A., Bouhedja A., Talhi K.

Mining Science

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2015

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Vol. 22

171--180

EN

The Tamazert-Jijel kaolin deposit is located in eastern Algeria, It was formed during a process of hydro-thermal alteration of feldspars rich in potassium. Kaolin, obtained at the mine, mainly contains varying amounts of impurities such as iron oxide (Fe2O3) and anatase (TiO2). These components negatively affect the quality of the commercial product. This research was performed to improve the quality of kaolin to be used in the paper industry with the goal of reducing the impurities of iron and titanium oxides. Different sized fractions of the original sample were analyzed by XRD. The results obtained showed that the mineralogical composition is: quartz, muscovite, kaolinite, dolomite, albite and orthoclase. Kaolin, like all clays, has a thin dissemination of minerals throughout it. After processing kaolin, the particle size fraction of less than 45μm, corresponding to the liberation mesh size, was retained for purification by chemical treatment with different acids of different concentrations (hydrochloric acid, sulfuric acid, acetic acid), heated to boiling point temperatures. The kaolin samples treated with the various acids above were analyzed by X-ray fluorescence and by XRD. The results obtained from the sample treated with hydrochloric acid show that the iron oxide content of acid is reduced by 1.65% to 0.88%. Meanwhile, the brightness of the sample reached 90% under the effect of the treatment with hydrochloric acid at concentration of 2 mole/dm3.

8

Assessing influence of hydrochloric acid leaching on structural changes and bleaching performance of Nigerian clay from Udi

Ajemba R. O., Onukwuli O. D.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 1

349--358

EN

Clay from Udi in Nigeria was mined, ground, and acid-leached at different concentrations of hydrochloric acid to produce adsorbents of varying properties. The raw and acid-leached samples were characterized using x-ray fluorescence (XRF) and Fourier transforms infra-red spectroscopy (FTIR) to examine the structural modifications in the clay as a result of acid-leaching. The analysis showed that the acid-leaching process caused several modifications of the clay samples. The surface area, Si/[Al + Fe + Mg] ratio, adsorption capacity were found to have increased in the acid-leached samples. The acid-leached samples were tested in order to ascertain their performance in bleaching palm oil and it was observed that the bleaching efficiency increased from 29.8% to 66.7%. The acid-leached sample prepared with 7M hydrochloric acid yielded an adsorbent that was efficient in bleaching palm oil under the experimental conditions. The isotherm analysis showed that the bleaching process followed the Freundlich equation.

9

Factors influencing preparation of polyaniline doped with hydrochloric acid

Chuanyu S, Yu W.

Materials Science Poland

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2014

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Vol. 32, No. 4

521--525

EN

Factors influencing the reaction of chemical polymerization during aniline doping with hydrochloric acid (HCl) have been studied in this work. The optimal parameters for the preparation of polyaniline were determined as follows: aniline concentration – 4 mass %, molar ratios of oxidant (NH4)2S2O8:aniline – 1.2:1 and 1.3:1, the concentration of dopant – 1 mol/L. Fourier transform infrared spectroscopy (FT-IR) was applied to characterize the structure of polyaniline.

10

Selektywna hydroliza pierścienia β-laktamowego 4-oksoazetid-2-ylofosfonianu dimetylowego

Malinowska B.

Przemysł Chemiczny

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2011

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T. 90, nr 5

907-909

11

Optimization of dolomite ore leaching in hydrochloric acid solutions

Abali Y., Bayca S. U., Arisoy K., Vaizogullar A. I.

Physicochemical Problems of Mineral Processing

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2011

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Vol. 46

253-262

EN

In this study, the Taguchi method was used to determine the optimum conditions for leaching of dolomite ore in hydrochloric acid solutions. The experimental parameters were leaching temperature, solid-to-liquid ratio, acid initial concentration, leaching time and stirring speed. The following optimum leaching parameter levels were found: temperature 50°C, solid-to-liquid ratio 2%, acid concentration 20 g/cm3 (2 mol/dm3), stirring speed 450 rpm, leaching time 5 min. Under the optimum process conditions, the dolomite ore leaching efficiency was about 83%.

PL

Wykorzystano metodę Taguchi do określenia optymalnych warunków ługowania rudy dolomitowej w roztworach kwasu solnego. Badano takie parametry jak temperatura, stosunek fazy stałej do ciekłej, początkowe stężenie kwasu, czas ługowania i prędkość mieszania. Ustalono, że optymalnymi parametrami są: stosunek fazy stałej do ciekłej 2%, początkowe stężenie kwasu 20 g/cm3 (2 mol/dm3), prędkość mieszania 450 rpm, czas ługowania 5 min. W tych warunkach wyługowanie dolomitu było około 83%.

12

Quaternary phosphonium salts as effective extractants of zinc(II) and iron(III) ions from acidic pickling solutions

Marszałkowska B., Regel-Rosocka M., Nowak Ł., Wiśniewski M.

Polish Journal of Chemical Technology

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2010

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Vol. 12, nr 4

1-5

EN

Extraction of zinc(II) and iron(III) from hydrochloric acid solutions using quaternary phosphonium salts, CyphosŽ IL 101, CyphosŽ IL 104, CyphosŽ IL109 and CyphosŽ IL 111 in mixtures with toluene, was studied. Trihexyl(tetradecyl)phosphonium chloride (CyphosŽ IL 101) and trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (CyphosŽ IL 104) showed the best zinc(II) and iron(III) extraction abilities. After three stages of zinc(II) extraction with CyphosŽ IL 101 and CyphosŽ IL 104 the efficiencies were 100 and 93.6%, respectively. Total iron(III) transport to the organic phase was achieved after two separation stages and amounted to 82.1 and 100% for CyphosŽ IL 101 and CyphosŽ IL 104, respectively. Zinc(II) and iron(III) could be effectively stripped from the loaded organic phases with 0.5 mol dm-3 sulfuric acid. The more hydrophobic the character of the anion type of phosphonium salts, the lower the efficiency of extraction.

13

Odzyskiwanie kwasu solnego z mieszaniny HCl-H2SO4

Tomaszewska M. U., Surowik A., Mientka A. M.

Przemysł Chemiczny

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2008

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T. 87, nr 5

596-599

14

Leaching of nickel from spent catalysts in hydrochloric acid solutions

Miazga B., Mulak Wł.

Physicochemical Problems of Mineral Processing

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2008

|

Vol. 42

179-186

EN

The results of hydrochloric acid leaching of nickel from spent catalysts used for methanation of small quantities of carbon oxide from hydrogen and ammonia synthesis gases (RANG-19), as well as for hydrogenation of benzene to cyclohexane (KUB-3) are reported. The effects of acid concentration, temperature, solid-to-liquid ratio and reaction time on nickel and aluminium leaching were examined. The leaching of nickel is more affected by temperature in the case of KUB-3 catalyst than RANG-19. After one hour leaching at 60 C in 3.0M HCl solution the extraction of nickel from RANG-19 catalyst amounts to 74%, whereas for KUB-3 after 45 min of leaching extraction of nickel is 99%. The highest leaching efficiency of nickel from both the catalysts are found to be: 3.0M HCl solution, tem perature 60C, solid to liquid ratio of 1/10, particle size 3-8 mm. In these conditions 99% of nickel is extracted from KUB-3 catalyst after 3 hours of leaching, and 98% of nickel from RANG-19 after 4 hours of leaching, respectively.

PL

Przedstawiono wyniki ługowania niklu z dwóch zużytych katalizatorów: katalizatora metalizacji (RANG-19) oraz katalizatora uwodornienia benzenu (KUB-3), stosując roztwory kwasu solnego. Określono wpływ stężenia HCl, temperatury, stosunku fazy stałej do ciekłej oraz intensywności mieszania na wydajność ługowania niklu. Wykazano, że temperatura znacznie bardziej wpływa na szybkość ługowania niklu z katalizatora KUB-3 aniżeli z RANG-19. Po 1 godzinie ługowania w temperaturze 60C w 3.0M HCl ekstrakcja niklu z katalizatora RANG-19 wynosi 74%, podczas gdy z katalizatora KUB-3 po 45 min wyługowania niklu wynosi 99%. Najwyższą wydajność ługowania niklu z obu katalizatorów bez dodatkowego rozdrobnienia (granulki 3-8 mm) uzyskano w 3.0M roztworze HCl, w temperaturze 60C przy stosunku fazy stałej do ciekłej 1/10. W powyższych warunkach ekstrakcja niklu z katalizatora KUB-3 wynosi 99% po 3 godzinach ługowania, natomiast 98% niklu wyługowano z katalizatora RANG-19 po 4 godzinach ługowania.

15

Methods of regeneration of spent pickling solutions from steel treatment plants

Regel-Rosocka M., Cieszyńska A., Wiśniewski M.

Polish Journal of Chemical Technology

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2007

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Vol. 9, nr 2

42-45

EN

Facing the still growing demand for metals, particularly for zinc, the recovery of metals from secondary sources should be considered. Spent pickling solutions can be the source of valuable products such as hydrochloric acid, zinc or iron salts or even metallic zinc. The selection of an efficient, selective and economical method for the regeneration of such solutions is a key issue for hot dip galvanizing plants, especially in reference to strict environmental protection regulations.

16

Extraction of palladium (II) ions from chloride solutions with phosphonium ionic liquid CyphosŽIL101

Cieszyńska A., Regel-Rosocka M., Wiśniewski M.

Polish Journal of Chemical Technology

|

2007

|

Vol. 9, nr 2

99-101

EN

The extraction of palladium(II) from hydrochloric acid solutions of various concentrations in the presence of different amounts of sodium chloride with phosphonium ionic liquid CyphosŽIL101 in toluene was investigated. The extraction of Pd(II) is very effective. The percentage extraction of Pd(II) from 0.1 mol dm-3 HCl solution amounts to 97% with CyphosŽIL101. Both the increase in HCl concentration and the presence of NaCl have a negative influence on the extraction. The extent of extraction from 0.1 mol dm-3 HCl solution in the presence of 0.5 mol dm-3 NaCl is about 80% and from 3 mol dm-3 HCl is lower and amounts to 56%. The extraction of Pd(II) from aqueous 0.1 mol dm-3 HCl and from 0.1 mol dm-3 HCl in the presence of 0.5 mol dm-3 NaCl with this phosphonium ionic liquid is rapid and the equilibrium is achieved after 1 - 2 minutes. The extraction of Pd(II) from aqueous 3 mol dm -3 HCl is slower and the equilibrium is achieved after 5 - 6 minutes.

17

Cathode materials for electrolysis of hydrochloric acid

Nawrat G., Parla A., Nieużyła Ł., Simka W.

Polish Journal of Chemical Technology

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2006

|

Vol. 8, nr 3

41-44

EN

The paper presents the results of investigations on silver cathodes with coatings obtained by means of thermal method to be used in the electrolysis of hydrochloric acid. Active coatings based on precious metals including platinum have good corrosion resistance and low overpotential of hydrogen owing to thermal decomposition of the respective salts on a silver substrate covered with a sublayer of gold. The values of hydrogen overpotential in 22% hydrochloric acid at 70°C amount to 70 mV at the current density of j = 1 kA/m2.

18

PENTOL'S experience to restructure emission monitoring systems in such a way as to meet waste fuel combustion requirements

Filipowski K.

Environment Protection Engineering

|

2006

|

Vol. 32, nr 3

39-46

EN

Current regulations state the scope of Continuous Emission Monitoring Systems depending of the fuel burnt. If waste fuels are combusted three additional measurements have to be carried out continuously, i.e., the concentration of HCl, HF and total organic carbon. This paper reviews available measuring techniques required by regulations. They differ from those applied in basic measurements, therefore the retrofit of existing analysers is almost impossible (except of that for HCl determination). The results achieved are discussed. The concept of CEM systems recently implemented by PENTOL in three Polish cement plants is presented. The experience gained allows a conclusion that the systems described in the paper are characterized by the features declared.

PL

Przepisy precyzują zakres pomiarów ciągłych do celów monitoringu emisji w zależności od rodzaju spalanego paliwa. W porównaniu z instalacją energetycznego spalania paliw, spalanie bądź współspalanie odpadów wymaga dodatkowo ciągłego pomiaru stężenia chlorowodoru, fluorowodoru i całkowitego węgla organicznego. Przeanalizowano dostępne technicznie i dopuszczone przez przepisy metody pomiarów tych związków. Optymalne techniki pomiarowe różnią się od technik stosowanych do pomiarów podstawowych, co uniemożliwia (poza pomiarem HCl) rozbudowę istniejących analizatorów. Omówiono problem interpretacji uzyskanych wyników pomiarów całkowitego węgla organicznego. Opisano koncepcję pomiaru emisji zrealizowaną w ostatnich latach w trzech polskich cementowniach.

19

Wydzielanie chlorowodoru z roztworów odpadowych metodą destylacji membranowej

Gryta M.

Przemysł Chemiczny

|

2005

|

T. 84, nr 10

745-749

PL

Przedstawiono możliwość zastosowania destylacji membranowej (MD) do rozdzielania odpadowych roztworów chlorowodoru. Do badań zastosowano ścieki powstające podczas regeneracji kationitów roztworem kwasu solnego. Omówiono wpływ parametrów procesowych, takich jak temperatura i skład roztworu zasilającego, na wielkość wydzielanego przez membrany strumienia wody i chlorowodoru. Porównano przebieg procesu MD w układzie jedno i kilkustopniowym. Wskazano na zagrożenia operacyjne, wynikające z wytracania się soli w module membranowym. Zaproponowano układ technologiczny umożliwiający odzyskanie i zawrócenie wody oraz części nieprzereagowanego kwasu do procesu regeneracji kationitu.

EN

Two waste solns. withdrawn from a cation-exchange resin regeneration step, contg. Na 2250, 846; Ca 3570, 3410; Mg 1380, 1020; K 834, 310; Fe 14, 10; Mn 10, 7; Cl 56 400, 48 700; and SO4 125, 29 ppm (HCl 40 600, 37 600 ppm), were membranedistd. at 358 K through PP membranes, total porosity 73%, pore size 0,2 µm, and ext./int. diam. ratio 2.6/1.8. The feed and the distillate were passed in cocurrent at 0.14 and 0.05 m/s, resp. In a batchwise single-stage membrane distn., the permeate HCl concn. varied much. With the feed added continuously and the concentrate withdrawn partially, the compn. was stable. A 4-stage system gave nearly pure water and a HCl soln. As water was sepd. in ca. 83%, CaSO4 could ppt. in the feed. At stage I and II, the distillate contained 0.5 and 1.2 g HCl/l., resp.; at higher stages the flux was richer in HCl.

20

Ekstrakcyjny odzysk cynku(II) z roztworów potrawiennych

Regel-Rosocka M., Miesiąc I., Szymanowski J.

Przemysł Chemiczny

|

2005

|

T. 84, nr 5

357-359

PL

Badano proces ekstrakcyjno-reekstrakcyjnego wydzielania cynku(II) z roztworów potrawiennych kwasu solnego za pomocą fosforanu tributylu (TBP) w układzie dwóch mieszalnikówodstojników. Redukcja żelaza(III) do żelaza(II) gwarantuje wysoką selektywność ekstrakcji cynku(II) wobec jonów żelaza. Propozycja procesu technologicznego odzysku cynku(II) obejmuje wstępne oczyszczanie roztworu ze związków powierzchniowo czynnych, redukcję żelaza(III), ekstrakcję cynku(II) oraz reekstrakcję cynku(II) za pomocą wody z ekstraktu TBP.

EN

A feed contg. Zn(II) 5g/L, HCl 1.8 or 10%, and Cl⁻ 5 mols/L was extd., 0.2 L/h, in a system of two mixers-settlers with 100% tributyl phosphate (TBP). From the org. phase, the Zn was reextd. with deionized water. The Zn(II) extn. and reextn. isotherms showed an org./water phase ratio of 0.5, two countercurrent TBP extn., and three countercurrent H2O reextn. stages to be required to reduce Zn(II) concn. from 15 to ~0.1 g/L; the loaded org. phase contained 30 g Zn(II)/L. The one- and two-stage recoveries of Zn(II) were 60 and 73.2%, resp. Dialkyl-phosphoric and phosphinic acids used as extractants proved ineffective; trialkylphosphine oxides and tri and dialkylamines made the reextn. step difficult. Prior redn. of Fe(III) to Fe(II) is necessary.