GeolCarp_Vol50_No5_394

GEOLOGICA CARPATHICA, 50, 5, BRATISLAVA, OCTOBER 1999

395404

MINERALOGY AND GEOCHEMISTRY OF ACID MINE

Fe-PRECIPITATES FROM THE MAIN SLOVAK MINING REGIONS

OTÍLIA LINTNEROVÁ

, VLADIMÍR UCHA

and VLADIMÍR STREKO

Department of Mineral Deposit Geology, Faculty of Science, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic

Geological Institute, Faculty of Science, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic

(Manuscript received May 26, 1998; accepted in revised form December 9, 1998)

Abstract: The Fe-ochre precipitates from three mine districts of Slovakia (Smolník, Banská tiavnica and Pezinok)

were studied. The X-ray diffraction, electron microscopic methods (TEM, SEM) with elemental X-ray analyses and

the selective dissolution method were used to make mineralogical phase characteristics of Fe-ochre precipitates.

Many fresh precipitates are X-ray amorphous, but in the extremely fine-grained material it is possible to identify some

Fe-mineral phases like schwertmannite and ferrihydrite. In the strongly acid degraded and artificial soils mainly

amorphous ferric oxyhydroxide is found. Unstable oxyhydroxides, oxyhydroxysulphate and amorphous Fe-phases

were dissolved by acid ammonium oxalate solution (pH 3) and by 1 M HCl. All free iron (Al, Mn) compounds of the

samples were extracted by dithionite-citrate-bicarbonate solution. The extracts were analyzed for Al, Fe, Zn, Pb, Cu,

As, Cd, Mn by the AAS, AES-ICP methods. Samples with different contents of Fe-phases (1099 wt. % of samples)

and formed over a wide pH range (2 to 7) were analyzed. The ochres formed under strongly acid conditions contain

mainly high concentrations of Al. The ochres formed in slightly acidic or neutral conditions are enriched in Cu, Pb,

Zn, Mn and As. Such conditions were found in the drainage of inactive tailing impoundments. The element attenua-

tion by Fe-ochres are controlled to a great extent by pH and by sulphate concentrations. The comparison of oxalate

and HCl extract concentrations show that analyzed elements are attenuated by the active or poorly crystalline Fe-

phases to a great extent.

Key words: Acid mine drainage precipitate, aluminium, Fe/oxyhydroxide, mine acid water, mine waste pollution,

microelements, pH-dependence, poorly crystalline phases, selective dissolution.

Introduction

Theoretically, the Fe-oxides/hydroxides or oxyhydroxides can

effectively adsorb our bind potential pollutant elements (met-

als) dissolved in waters (Cornell 1991; Schwertmann & Cor-

nell 1991; Schwertmann et al. 1979; Schwertmannn & Taylor

1989; Kooner 1992, 1993; Fuge et al. 1994). We are studying

the processes of Fe-oxyhydroxide phase formation in acidic

mine environments. Intensive pyrite oxidation in mine and

mine wastes can produce a large amount of free sulphuric acid

and/or extremely acid drainage water (pH < 3). These process-

es occurred mainly in sulphidic and coal mines (Jambor &

Blowes 1994; Alpers & Blowes 1994; Wieder & Novák 1995).

Acid water dissolves ore and rock minerals and the concentra-

tions of Fe, Al, Mg, Ca and metals (Zn, Cu, Mn, Ni, ...) in wa-

ter increased significantly. Fe (III)-oxides/hydroxides can be

precipitated after mixing or diluting the acid mine water with

fresh surface water and the characteristic red-brown (ochres)

Fe oxides are precipitated in drainage channels or other places

of mine water discharge (mine dumps, tailing impoundments).

The precipitates are very fine-grained and the high specific

surface of precipitates is one of the controlling factor of the re-

moval of the dissolved elements to the solid phase. However,

the formation of extreme acid mine waters has produced a spe-

cific or naturally unusual environment.

In the presented paper the formation of Fe-ochres in some

mine district of Slovakia is studied. The acidification of sur-

face water and soil is the serious environmental problem in the

vicinity of Smolník, Banská tiavnica-obov and Pezinok

mines, mine dumps and mill tailing impoundments (ucha et

al. 1995, 1997; Jako et al. 1997; Lintnerová 1996; Lintnerová

& Líková 1997; Trtíková 1997; Trtíková et al. 1996).

The aim of the paper is to identify the mineralogical com-

position of Fe-ochre deposits and determine the concentra-

tion of some environmentally important elements in their

precipitates from mine areas of Slovakia. Fe-precipitates se-

lected for the study were originated in various environments

such as drainage channels, soils, stream sediment and under

different conditions (pH, SO

concentrations).

Description of localities and samples

The studied Fe-oxide/hydroxide samples come from three

important mining districts of Slovakia.

1. The mine field of Smolník is situated in the Slovenské

Rudohorie Mts. (Eastern Slovakia, Fig. 1). The abandoned Cu-

Fig. 1. The localization of the investigated mine districts of Slovakia.

396 LINTNEROVÁ, UCHA and STREKO

pyrite mine (Bartalský 1993) is flooded and strongly acid wa-

ter (pH 2.83.8) discharges from the mine (Jako et al. 1996).

The Fe-ochre precipitates collected for analyses are formed

along the banks of the Smolník Stream, where acid mine water

penetrating into the stream is mixed with fresh water and caus-

es a dramatical decrease in its pH from about 7 to 4.04.5. The

Fe-ochres are also precipitated on the anthropogenic soil sur-

face (pH 3.4) of the Smolník mill tailing impoundment and in

the water drainage collector under the tailing impoundment

(Table 1).

2. The mine field of Banská tiavnica (Central part of Slo-

vakia, Fig. 1). Fe-precipitates were collected from the aban-

doned mill tailing impoundments of Lintich and Sedem ien

and from the obov mine dump. A large amount of pyrophyl-

lite-pyrite gangue rock in the obov quartzite mine was exca-

vated and deposited on the dump. The intensive pyrite oxida-

tion in the dump produced extremely acid water (pH 1.72.4)

with a high content of total dissolved solids (ucha et al.

1997). Fe-oxyhydroxides are formed as the precipitates from

drainage water when it is mixed with the fresh water as well in

the degraded soils. The most acid soils (area of 35,000 m

) are

desertified and deeply eroded.

Mill tailings of Pb-Zn ore processing were deposited until

1987 into the Sedem ien impoundment. The ochreous (ox-

isoil) horizons are formed in the soils in the vicinity of the

impoundment (Lintnerová & Líková 1997). Samples of

drainage precipitates and ochreous soils were collected

(Table 1).

The mill tailing impoundment of Lintich has been inactive

since 1974 and no acidification processes can be detected there.

The surface of the impoundment is covered by the secondary

minerals (gypsum) and sometimes a hardpan with Fe-oxides can

be found in the near surface horizons. Higher contents of fresh

Fe-precipitates are formed in the drainage channel of the im-

poundment where they were collected (Table 1).

3. The Pezinok (pyrite-Au-Sb) mine field (Western Slova-

kia, Fig. 1). The Fe-precipitates formed in the drainage chan-

nel of the mill tailing impoundment of Kolársky Vrch and on

the stream bank near the abandoned pyrite mine (Augustín)

were analyzed (Table 1).

Table 1: The analyzed samples from Smolník, Banská tiavnica and Pezinok. The samples were collected in 1995 to 1997 from streams,

drainages and soils. More details about pH and extractable Al*-analyses can be found in ucha et al. (1997), Lintnerová & Líková (1997).

Locality

Samples

Samples No.

*A l(KC l) mg/kg

Smolník
Smolník-mine

Stream sediment and
mine drainage precipitates (Sm/95, Sm/96)

2.64.8

Smolník-impoundment

Drainage water precipitates SmOd/96

3.17.1

Banská tiavnica
obov-dump

Acid soils (ob/96, P/97)

2.05.1

12101.5

Stream sediments (B22/97)

2.06.5

Sedem ien-impoundment

Anthropogenic soils (BA-BG 1997, 1996)

1.67

6211.1

Acid soils (B/97, E/97)

1.75.6

2382.7

Lintich-impoundment

Drainage water precipitates (1996,1997)

6.87.2

Pezinok
Pezinok-mine

Stream sediment (Pez/96)

2.33.2

Pezinok-impoundment

Drainage water precipitates (POd/96)

6.87.3

Methods

The X-ray diffraction analyses of samples were performed

on a Philips PW 1710 equipped with Ni-filtered CoK

radia-

tion and CuK

radiation. Transmission electron microscopy

(TEM) study was done on the JEOL JEM-2000 microscope

and elemental X-ray microanalyses using the 10,000 AN

LINKenergy dispersive analyzing system (EDS). Scan-

ning electron microscopes (SEM) TESLA BS300 and JEOL

JXA 840A were used for investigation of sample surface

covered by gold.

The field and laboratory pH measurements were done by

standard potentiometric methods. Soil pH was determined

after mixing the soil sample with distilled water and in 1 M

KCl (mixture 1:2.5). The treatment with 1 M KCl was used

for determination of exchangeable Al in the soil samples by

AES-ICP methods. The characteristic intervals of pH and Al

values are summarized in the Table 1.

Dried Fe-precipitates were treated by dithionite-citric-bi-

carbonate (DCB) at 85 °C (method Mehra & Jackson 1960;

Schwertmann & Taylor 1989; van Reeuwijk 1995). The less

stable or poorly crystalline and amorphous Fe-phases such as

ferrihydrite or schwertmannite (most probably together with

the amorphous compound of Al and Si) were extracted by

acid ammonium oxalate in the dark to eliminate photoreduc-

tion (van Reeuwijk 1995; Bigham 1994). Goethite, hematite

or well ordered lepidocrocite are not dissolved to any great

extent unless some source of Fe

cations is presented

(Schwertmann & Taylor 1989). Extractant was prepared by

mixing 0.2 M ammonium oxalate and 0.2 M oxalate acid so-

lutions. The 1 M HCl dissolution was applied to the same

samples as oxalate extraction. The HCl dissolves Fe and Mn

oxides (coating on the grains), carbonate and can also replace

trace element ions adsorbed on organic and inorganic materi-

al. Insoluble residues were determined gravimetrically.

Fe, Cu, Pb, Zn, Mn, As were analyzed in extracts by AAS

and Al by AES-ICP methods. The SO

concentrations in

the distilled water (Table 4, DCB-results) and in 1 M HCl ex-

tracts were determined by the gravimetric and colorimetric

methods. The Si was analyzed by the colorimetric method.

MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 397

Results

Mineralogical phase analyses

The poor crystallinity and high variability in mineral phase

formation were characterized in the ochre precipitates formed

in a broad range of pH conditions. The majority of studied

samples were not pure Fe-precipitates and they contain com-

mon shale and soil minerals (mainly quartz, phyllosilicates

and +/- feldspar).

The sample set of the fresh precipitates and hardpan-like de-

posits of Smolník Stream represent a strongly acidic environ-

ment with high sulphate contents (pH in range 2.8 to 4.8, and

over 1000 mg/l of sulphates). The mineralogy of the sample

was characterized in detail by Lintnerová (1996). The most

common phase is jarosite which can be easily identified in the

X-ray diffraction profiles of all samples. Goethite was identi-

fied only in the hardpan samples and after oxalate treatment

of fresh sample (Fig. 2, sample Sm1/96). Amorphous and

poorly crystalline Fe-ochre phases such as schwertmannite are

dominant in the fresh Smolník precipitates (Fig. 2) and repre-

sent typical ochres formed under the condition of acid mine

drainage (Bigham et al. 1990; Murad et al. 1994; Bigham et al.

1997).

The Fe-ochres precipitated near the abandoned sulphidic

mine near Pezinok (Pez1/96, Pez2/96, Tables 1 and 4) are

formed at about the same pH conditions as in the Smolník

area. The X-ray analyses, TEM investigation and selective

dissolution results detected an amorphous to poorly crystal-

line character of the ochre material. The ochre forms aggre-

gates with elongated protocrystals 50 to 150 nm in size. The

surfaces of pyrite grains in the black shells are covered by

jarosite.

The ochre precipitates in the Banská tiavnica-obov area

are formed by stream-bank percolating and slightly acidic

waters (pH

≈

5) (ob2/96 in the Tables 15). The X-ray pro-

files of precipitates show only one low and broad band

(0.2450.260 nm), characteristic for amorphous material.

The TEM micrographs show poorly crystalline material of

globular shape with needle-like protocrystals (Fig. 3). The

dominant Fe content with slightly increased Si and no S con-

centrations were detected in globular aggregates. Since more

than 80 % of the Fe-precipitates were dissolved by acid ox-

alate (ob2/96, Table 2) we assume that the precipitates are

of ferrihydrite-like character. Increased content of Si relative

to Al (Table 3) decreases probably the crystallization of pre-

cipitate.

The ochreous samples precipitated from the mill tailing

impoundment drainage (pH near neutral) were collected

from all three study area (Table 1). A high proportions of the

samples are amorphous to poorly crystalline Fe-oxyhydrox-

ide phases easily dissolved using acid ammonium oxalate

treatment (Table 2). The TEM micrographs (Fig. 4 AD)

show characteristic morphology of grain aggregates from the

Smolník and Lintich (Banská tiavnica) impoundment pre-

cipitates.

Fig. 2. X-ray profiles of the Smolník samples Sm1/96 and Sm3/96: natural and after acid ammonium oxalate treatment O. (Chchlo-

rite, Mmuscovite, Jjarosite, Qquartz, Ggoethite, Flfeldspar, Schschwertmannite.)

2 the ta, CoK

1/96O

1/96

3/96O

3/96

Fl J

398 LINTNEROVÁ, UCHA and STREKO

Ochres in the soil samples

The upper ochreous (015 cm) horizon and the lower (15

30 cm) dark-brown horizon with local Fe-oxide aggregates

were created by acid leaching in the obov (Banská tiavni-

Table 2: The results of selective dissolution of the ss = stream sed-

iment precipitates, TI = tailing impoundment drainage precipi-

tates, soil and A = anthropogenic soil samples. Insoluble residua

(IR) were determined by the gravimetric method: the dissolved

part = (100-IR) wt. %.

Dissolved part

Extracts

HCl

Acid oxalate

Material

Samples

wt. %

Sm2/95

62.7

59.1

ss-precipitate

Sm10/95

48.3

44.3

ss-precipitate

Sm3/95

92.9

89.1

ss-precipitate

SmOd/96

80.6

70.1

TI -precipitate

ob2/96

99.2

82.5

ss-precipitate

ob3/96

20.3

17.3

soil

P2/97

25.9

16.6

soil

BA/97

24.3

20.4

A-soil

BE/97

14.8

9.4

A-soil

BG/97

19.6

13.2

A-soil

E9/97

11.2

9.8

A-soil

B3/97

11.4

8.9

soil

B6/97

20.7

13.2

soil

B22/97

23.1

15.5

ss-precipitate

Table 3: Large differences can be seen between Si and Al contents

determined in HCl and acid oxalate extracts in the Smolník and

obov samples (see also Tables 2 and 4). The ochre formed in neu-

tral impoundment drainage SmOd/96 has about the same Al

content in both extracts. ob2/96, probable ferrihydrite, contained

the lowest Al and relatively high Si contents.

HCl extracts

Acid oxalate extracts

Samples

mg/kg

Sm2/95

42.7

23820

16100

40.1

1200

650

Sm10/95

38.8

26120

23300

37.6

11010

1340

Sm3/96

43.9

29400

14400

41.8

2240

680

SmOd/96 41.1

33240

16700

35.6

30260

5670

ob2/96

46.7

260

42300

43.2

3420

ob3/96

28.3

23230

18200

23.5

5780

1290

Table 4: The results of AAS analyses of DCB extracts. pH and

were determined as the distilled water extracts. 0values less

than the detected limit of the element in the extract. The results are

in mg of element per l kg of ochre.

*SO

Dithionite-citrate-bicarbonate

Samples units mg/kg

mg/kg

Sm2/95

2.6

4533

34.4

Sm8/95

3.7

37.03

293

108

249

Sm9/95

3.9

39.12

234

126

226

Sm10/95

4.1

41.15

196

134

131

Sm1/96

2.6

19434

45.41

180

Sm2/96

2.9

7364

47.43

685

Sm3/96

3.5

13532

50.71

SmOd/96 6.8

2912

48.86 24268

0 1209 1128

3223

ob1/96

3.2

694

8.33

386

161

228

163

ob2/96

4.7

8333

56.66

9038

ob3/96

2.8

781

15.62

359

156

125

165

Lintich

6.91254940.78 23137

494559 145

222

Pez1/96

2.6

18333

50.86

120

354

Pez2/96

3.2

11867

48.13

991

POd/96

7.1

3823

38.01

137647

ca) soils. Such soils are devoid of vegetation and the soil sur-

face is covered by gypsum and jarosite (Fig. 3A). Neoformic

pseudocubic crystals of jarosite can be commonly found in

the soil fraction < 2

m (Fig. 3 B).

Fe-oxyhydroxides coated the surface of soil particles repre-

sented about 20 wt. % of soil samples from the upper horizon

(Table 2). X-ray profiles of the soil sample show the broads at

d ~ 0.25 nm bands or an increased background but no crystal-

line Fe-mineral phase can be identified. Goethite is formed in

the deeper horizon of the soil but amorphous and/or poorly

crystalline Fe-phases are also presented.

The major part of the Fe-compounds are extracted by acid

oxalate (Table 3). Both samples come from the upper (025

cm) horizon and were sampled in 1996 and 1997 at the same

place. The same association of mineral phases was identified

in the acid anthropogenic soil of the tailing impoundment dam

(Sedem ien, Banská tiavnica). The dam soils are shallow

and no soil horizons were developed there. Tailing material

(fine sand) contains about 5 % of sulphides, mainly pyrite, in

the surface bed of the impoundment (below the shallow soil)

and sulphide oxidation is the source of extreme soil acidity

(Table 1). The pyrite grains are dissolved and Fe-oxyhydrox-

ides and sulphates coat the grains (Fig. 5B, C). The pH field

measurements document the increased tendency of soil acidifi-

cation and oxisoil horizon formation in the near-impound-

ment soils (Lintnerová & Líková 1997).

The Fe-compounds represent 10 to 25 wt. % of the soil

samples and a large part of the Fe-phases were dissolved by

acid ammonium oxalate (Table 2).

Microelement analyses

The tables (Tables 3, 4 and 5) contain the results of the

AAS-ICP analyses of the soluble Fe (III)-oxyhydroxide

phases. The results are expressed as element contents in mg

per kg of Fe dissolved phase, because the contents of soluble

Fe (III) phases are in the broad weight % range in our sample

set (Table 2). We can see, that the analyzed soil samples con-

tained only from 10 to 26 % of soluble phases but mine

drainage water precipitates contain much more of these phas-

es (48 to 99 %). The results in Table 4 are representative

analyses of DCB extracts from acid mine drainage ochres of

the Smolník, Banská tiavnica and Pezinok mine areas to-

gether with two analyses of degraded soil from obov (ob1

and ob3). Total soil analyses and mine water analyses from

the obov area (Banská tiavnica) presented by ucha et al.

(1997) are given in Table 7. The chemical characteristics of

the Smolník mine, stream water and stream sediments (total

analyses) are summarized in Table 6. The results of parallel

oxalate and HCl extract analyses of precipitates and soils are

presented in the Tables 5A and 5B. The relative concentra-

tion ratios (ochre/water) can be calculated for some elements

only and values with stars were used (Fuge et al. 1994).

Fe-phases are amorphous to very fine-grained (~ grain size

0.1 to 0.3

m) with high specific surface areas. The high spe-

cific surface area and high hydration of Fe-oxides are con-

trolling factors of the physical and chemical sorption or bind-

ing (mechanism and kinetic) of the dissolved elements. Other

MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 401

amorphous phases such as SiO

and Al-hydrated compounds

can be present and/or neoformed in the degraded acidic soils

as well. Unstable or intermediate phases of Fe (III) oxyhy-

droxide are dissolved by acid ammonium oxalate treatment.

The Si and Al contents in analyzed samples are listed in the

Table 3. 1 M HCl treatment led to the highest content of Si

and Al in solutions, probably due to much stronger attack not

only to iron ochres but to phyllosilicates as well. Only one

sample (precipitate formed in neutral condition SmOd/96)

shows about the same contents of Al in oxalate and HCl ex-

tracts. The analyses show, that the Fe-phases originated un-

der low pH condition contain mainly Al and other elements

are preserved in trace contents (Table 4). The variety of ele-

ments connected with Fe-precipitates increases with the in-

crease of the pH of their origins. High contents of Cu, Mn,

As, Zn were determined in the Fe-precipitates from tailing

impoundment (pH near neutral). The same pH-dependence

was observed for Fe-precipitates formed in acidified and an-

thropogenic soils (Table 5A, 5B).

Discussion

The studied mine regions are badly polluted and the con-

tents of some dissolved elements are many times higher than

environmentally accepted values for soil and waters. It is re-

ally important, that neoformed Fe-phases can effectively re-

move dissolved and potentially toxic elements from the mine

waters. On the other hand, the amorphous character and/or

relative instability of Fe-phases indicate some possibility of

retrograde metal releasing reactions in strongly acid mine en-

vironments. Under common soil or water conditions such

retrograde reactions are highly improbable as goethite or he-

matite can bind or adsorb soluble elements to a great extent

(Schulze & Schwertmann 1984; Schwertmann & Cornell

1991; Schwertmann & Taylor 1989).

It is clear that not only high acidity, but also increased

amounts of sulphates and other compounds must be factors

controlling Fe-oxyhydroxides or oxyhydroxysulphates for-

mation (Bigham 1994; Murad et al. 1994; Bigham et al.

1997). Only small amount of goethite is present in the rela-

tively older hardpan such as the Fe-deposits in the Smolník

Stream (Lintnerová 1996). The sulphate contents in the

Smolník precipitates are still high and the mine water is

oversaturated with respect to schwertmannite (Cambier et al.

1997). Selective dissolution of the ochres samples by acid

ammonium oxalate has verified the mineralogical results.

However, interpretation of the partial extraction results of

natural samples is not as simple as could be expected. The

stream sediments and soils (tailings) contained other phases

such as organic matter and phyllosilicates partially leached

by acid water. The various elements adsorbed on these phas-

es can be removed by HCl and as well by organic extractants,

such as oxalate acid or citric acid (Schwertmann & Taylor

1989; van Reeuwijk 1995; Bigham 1994; Stumm &

Sulzberger 1992).

It was found, that Al is enriched in ochres and the Al con-

centrations higher than 1 % were detected in some Smolník

samples. It can be expected, because Al is one of the most

Fig. 5. Banská tiavnica-Sedem ien mill tailing impoundment: A.

The surface of anthropogenic soils are coated by well crystal-

lized gypsum. B, C. Tailing pyrite grains are oxidized and second-

ary minerals are formed on the grain surface. The large number of

grain cracks are probably the result of the mill process.

402 LINTNEROVÁ, UCHA and STREKO

Table 5: The element concentrations analyzed both in 1 M HCl (A) and in acid ammonium oxalate (B) extracts of soil samples from the

Banská tiavnica mine area. 0less than 4000 mg/l in the extracts.

Samples

HCl

units

mg/kg

BA/97

1.6

19.45

9390

230

3950

240

1850

2630

12770

123400

BE/97

3.3

19.58

9860

200

3510

430

1550

9960

4320

5260

BG/97

6.6

19.89

25710

280

28310

1320

33230

80460

3460

11350

B3/97

1.7

24.12

22540

380

35130

630

4540

4370

E9/97

2.1

26.40

19620

140

11240

499

13550

571

B6/97

3.5

19.78

16870

250

7560

720

1550

3440

B22/97

3.9

24.36

44170

100

1170

170

1000

2430

P2/97

2.8

20.30

48790

2860

540

1120

8720

Samples

Acid ammonium oxalate

units

mg/kg

BA/97

1.6

12.24

7692

142

784

186

1030

1127

BE/97

3.3

17.67

2662

202

3088

426

1704

13206

BG/97

6.6

18.21

4400

144

7511

1745

8953

32170

B3/97

1.7

18.30

7254

266

12500

379

2455

2120

E9/97

2.1

25.00

6045

266

5840

328

2152

2049

B6/97

3.5

17.54

4173

174

3414

713

910

1897

B22/97

3.9

12.26

12976

116

581

142

387

1808

P2/97

2.8

11.41

12311

2293

591

724

10682

Table 6: Comparison of the Smolník Stream sediment, ochre and water analyses. Results of total analyses of stream sediments deposited

in the neutral and acid parts of the Smolník Stream (Jako et al. 1996) are in 1th- and 2nd-columns. Dithionite-citric-bicarbonate (DCB)

extract analyses of the same sample (Sm8/95) are given in the 3th-column. The acid water (4th-column) flowed into Smolník Stream and

ochres were precipitated (Sm2/95). The resulted stream water was still acidic (5th-column). The values with the stars are used in the ratio

calculation: Fe, As and Cu, were accumulated in the ochre precipitates.

Smolník mine

Stream sediment

(total analyses)

mg/kg

Stream sediment

(tot. anal. Sm8/95)

mg/kg

Ochre (DCB)

Sm8/95

mg/kg

Effluent mine

*water

mg/l

Stream water

mg/l

Ochre (DCB)

*Sm2/95

mg/kg

*Ratio

Ochre/water

(units

)

6.5

3.7

4.7

2.6

12667

492

4500

0.35

1953

232

6.10 %

7.05 %

553

4.02 %

9.51 %

37.03 %

1483

34.40 %

232

619424

140

0.186

0.026

<0.005

242

158

108

0.36

5.3

<0.004

<0.1

195

2.5

<0.1

2490.04

<0.005

1775

0.001

0.003

0.011

<0.005

0.25

0.38

<0.001

<0.1

0.027

<0.003

<0.1

pH dependent element and it is well known and documented

not only in soils but also in acid mine drainage waters (Tho-

mas & Hargrowe 1984; Nordstrom & Ball 1986; Hsu 1989;

Fuge et al. 1984). The other analyzed elements Zn, Pb,

Mn are depleted in acidic ochres.

Some element depletion can also be seen in the total

stream sediment analyses (Table 6). For example, the Zn and

Mn contents decreased in the acidified part of stream as the

Fe-content (ochre formation) increased. It is possible, that

the sulphate acidoxidic water are leaching the stream sedi-

ment reached-up to the typical Smolník mine elements in the

past (Table 6). It appears, that As is relatively enriched in the

acid ochres (Table 6). Arsenic can be adsorbed and/or copre-

cipitated by ferrihydrite and Fe-oxyhydroxysulphates in both

As (III) and As (V) valence forms. Arsenic (V) forms strong

anionic complex with Fe-phases in strong acid and oxidic en-

vironments (Webster et al. 1994). On the other hand, the As

concentration in the mine water is really low (Table 6) and it

is possible, that as bound in ochres is released from sediment

suspensions (Morse 1994; Calmano et al. 1994).

The Cu and Zn contents in effluent mine water are relatively

high, but only Cu is relatively enriched in acid ochres (Tables

4, 6). The stream water (pH 45) analyses showed that Zn is

available for transport in acidic stream water (Kooner 1993;

Fuge et al. 1994). The ochres formed in neutral drainage water

attenuated large amounts of Zn, Cu, Mn and As (Table 4) and

clearly document that the water mobility of the studied ele-

ments is pH-dependent. The Mn and Al contents (Tables 3 and

4) are high and it is possible that Al-hydroxides and Mn-ox-

ides are created in these near neutral conditions. Important

MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 403

determined. The available Al increase in the soils and in the

neoformed Fe-ochres indicated the leaching of phyllosilicate

(Tables 1, 3, 5A, B). The soil minerals are possible sources of

Ca and K for jarosite and gypsum formation in the soils. The

sulphate enrichments in the acidic water can selectively immo-

bilize such elements as Pb or Ba to a greater extent than others

(Fuge et al. 1994). The some enrichment with Pb appeared in

the studied strong acid soils (Table 5A, B), but the no direct con-

nections with the sulphate content can be shown up to now.

Conclusions

1. The studied Fe (III) oxide/hydroxide precipitates from

the Smolník, Banská tiavnica and Pezinok mine fields

represented (X-ray) amorphous to poorly crystalline fine-

grained material. A major part of the ochres is formed by

less stable Fe-oxyhydroxide and oxyhydroxysulphate phas-

es, such as schwertmannite and ferrihydrite and by well

crystallized jarosite as well.

2. A high contents of jarosite and free and/or poorly crys-

talline ferric oxyhydroxide are formed (10 to 25 % of free

Fe- oxides/hydroxides) in the upper (oxisoil-like) horizons in

the strongly acid (degraded and anthropogenic) soils.

3. The Fe-ochres can adsorb or coprecipitate an important

content of dissolved elements and the attenuation of ele-

ments is pH dependent. The Fe-ochres formed under the

strongly acid conditions removed from solutions mainly Al

and the concentrations of other analyzed elements is relative-

ly low. The ochres formed under slightly acidic or neutral

conditions are enriched in their Cu, Pb, Zn, Mn and As con-

tents. Such conditions were found in the drainage system of

the inactive tailing impoundments.

4. The comparison of the concentration of the acid oxalate

and HCl extracts show that the analyzed elements are attenu-

ated by the active or poorly crystalline Fe-phases to a great

extent.

5. The element distributions in the Fe-oxides/hydroxides

formed in degraded or anthropogenic acid soils is controlled

to a great extent by pH and sulphate concentration, but other

factors can be important as well.

Acknowledgements: We are thankful Dr. ¼. Pukelová from

Geological Institute of the Slovak Academy of Sciences Brat-

islava for X-ray analyses and Dr. Èaplovièová and Dr. J. Stank-

oviè for their assistance in electron microscopy investigation

(Central Laboratory of Electron Microscopy of the Faculty of

Science, Comenius University Bratislava). We are grateful to

anonymous reviewers for their large effort benefited the manu-

script. This research was supported by Scientific Grant Agency

(VEGA) of Ministry of Education of Slovak Republic and Slo-

vak Academy of Sciences (Grant No. 1/4090/97).

References

Alpers C.N. & Blowes D.W., 1994: Environmental geochemistry

of sulfide oxidation. Amer. Chem. Soc., 550, 1681.

Banásová V. & ucha V., 1998: Degradation of grassland after

Table 7: The comparison of the obov water, soil (ucha et al.

1997) and ochre analyses. The values with stars are used in the ra-

tio calculation.

*Effluent

dump water

Soil

analyses

Soil

analyses

*Ochres

Ochre/water

0-10 cm

10-30 cm

P2 0-25 cm

*ratios

mg/l

mg/kg

2.35

2.34

2.75

15980

7100

5800

3625

4.85 %

6.01 %

20.30 %

923

48790

286

320

8700

122

8.6

36.3

41.4

540

8.4

152

1120

133

140

191

2860

0.67 22.4

proportions of the analyzed metals can be sorbed by organic

matter, as was detected by IR spectroscopy of ochre samples

(SmOd/96) and also earlier (unpublished data). These process-

es were not investigated, but we can note that the bacterially

catalyzed pyrite oxidation and increased organic contents in

mine water were documented (Jako & Cicmanová, unpub-

lished).

The extremely high As contents were determined in the

amorphous ochres precipitated in tailings effluent water near

the Pezinok mine (Table 4). The pyrite-arsenopyrite associa-

tion of these ores is the first factor controlling the such high

As re-concentrations in the ochre precipitates. On the other

hand, the effluent water of this inactive impoundment can

mobilize a high content of As.

Our first results indicated, that the Banská tiavnica mine

wastes deposited in the Lintich and Sedem ien impoundments

should produce drainage water with comparable high element

concentrations. The ochres formed in near neutral conditions

can be Mn, As, Cu and Zn enriched according to the mineral-

ogical composition of the processed ores and mine wastes de-

posited into the impoundment. Total and selective dissolution

analyses of waste drainage waters and Fe-ochres will be done

to investigate these processes. However, the ochre-phase anal-

yses of the antropogenic and uncultivated soils near the tailing

impoundment of Sedem ien indicated an element mobiliza-

tion and the main factor controlling the element mobilization

is the formation of extreme acidity (Table 1, Table 5A, 5B).

The soil like those of wetland are formed in the lower border

of the impoundment and as the soil acidity decreased in this

soil (Table 5A, 5B, sample BG/97), the Pb, Cu, Zn and Mn

contents increased. Wetland is a very effective system for re-

mediation of acid mine and tailing waters (Blowes et al. 1994;

Wieder-Novák 1995).

The soil properties were monitored in the uncultivated area

around the obov mine in 1995 to 1997 and a high and in-

creased degree of soil degradation was identified (ucha et al.

1997). Acid water has flowed out of the mine dump percolated

into soils. On the one hand water with high contents of Fe, Al,

Mg, sulphate and other pyrite bearing metals has contaminated

soils and on the other acid-aggressive water has leached soils.

The free Fe-oxides have created a characteristic yellow-brown

oxisoil horizon. In the most acidic soils the increased contents of

exchangeable Al (Table 1 more than 1000 mg/kg in 1997) were

404 LINTNEROVÁ, UCHA and STREKO

strong soil acidification. Ekológia, 17, 2838.

Bartalský J. (Ed.), 1993: Smolník the town of cooper-ore mine.

Miner. slovaca, Monograph., 1368 (in Slovak with German

abstract).

Bigham J.M., 1994: Mineralogy of ochre deposits formed by sul-

fide oxidation. In: Jambor J.L. & Blowes W. (Eds.): Short

course handbook on environmental geochemistry of sulfide

mineral-wastes. Mineral. Assoc. Canada, 22, 103132.

Bigham J.M., Schwertmann U., Carlson L. & Murad E., 1990: A

poorly crystallized oxyhydroxysulfate of iron formed by bac-

terial oxidation of Fe (II) in acid mine waters. Geochim. Cos-

mochim. Acta, 54, 27432758.

Bigham J.M., Schwertmann U., Traina S.J., Winland R.L. & Wolf M.,

1997: Schwertmannite and the chemical modeling of iron in acid

sulfate waters. Geochim. Cosmochim. Acta, 60, 21112121.

Blowes D.W., Ptacek C.J. & Jambor J.L., 1994: Remediation and

prevention of low quality drainage from tailing impound-

ments. In: Jambor J.L. & Blowes D.W. (Eds.): Short course

handbook on environmental geochemistry of sulfide mine-

wastes. Mineral. Assoc. Canada, 22, 59102.

Cambier P., Dubíková M. & ucha V., 1997: Solubility equilibria

within acid sulfate water from Slovakian mine sites after

soilchem calculations. Book of abstracts of 2th Conference of

IGCP no. 405, ENVIWEATH, Bratislava, 1516.

Cornell R.M., 1991: Simultaneous incorporation of Mn, Ni and Co in

the goethite (

FeOOH) structure. Clay Minerals, 26, 427430.

Fuge R., Pearce F.M, Pearce N.J.G & Perkin W.T., 1994: Acid

mine drainage in Wales and influence of ochre precipitation

on water chemistry. In: Alpers C.N. & Blowes D.W. (Eds.):

Environmental geochemistry of sulfide oxidation. Amer.

Chem. Soc., Washington, 550, 261275.

Hsu P.H., 1989: Aluminum hydroxides and oxides. In: Dixon J.B.

& Weed S.B. (Eds.): Minerals in soil environment. Soil Sci.

Soc. America, Madison, Wisconsin, 331378.

Jambor J.L. & Blowes D.W., 1994: Short course handbook on en-

vironmental geochemistry of sulfide mine-wastes. Mineral.

Assoc. Canada, 22, 1438.

Jako V., Cicmanová S., Bajto P., Pramuka S., esták P., Baita J.,

Gajdo V., Rozimant K., Lintnerová O., Hornung L. & Galaj-

da J., 1996: Smolník the complete hydrogeological and

hydrochemical study of Cu-Fe deposit. Admin. rep., Aquipur

Comen., Bratislava, 1124 (in Slovak).

Lintnerová O., 1996: Mineralogy of Fe/ochre deposits formed

from acid mine water in the Smolník mine (Slovakia). Geol.

Carpathica Clays, 5, 5563.

Lintnerová O. & Líková M., 1997: Acidification of artificial soils

of Sedem ien mill tailing impoundment (Banská tiavnica,

Slovakia). Book of abstracts of 2th. Conference of IGCP no.

405, ENVIWEATH, Bratislava, 33.

Kooner Z.S., 1992: Adsorption of copper onto goethite in aqueous

systems. Environ. Geol. Water Sci., 20, 205212.

Kooner Z.S., 1993: Comparative study of adsorption behavior of

copper, lead, and zinc onto goethite in aqueous system. Envi-

ronmental Geol. Not., 21, 242250.

Mehra O.P. & Jackson M.L., 1960: Iron oxide removal from soils

and clays by dithionite-citrate system buffered with sodium

bicarbonate. Clays and Clay Miner., 7th-conf., 317327.

Murad E., Schwertmann U., Bigham J.M. & Carlson L., 1994:

Mineralogical characteristic of poorly crystallized precipi-

tates formed by oxidation of Fe

in acid mine sulfate waters.

In: Alper C.N & Blowes D.W. (Eds.): Environmental

geochemistry of sulfide oxidation. Amer. Chem. Soc., Wash-

ington, 550, 190200.

Nordstrom D.K. & Ball J.W., 1986: The geochemical behavior of

aluminum in acidified surface waters. Science, 232, 5456.

Schulze D.G & Schwertmann U., 1984: Influence of aluminium on

iron oxides X. The properties of Al substituted goethites.

Clays and Clay Miner., 19, 521529.

Schwertmann U. & Cornell R.M., 1991: Iron oxides in the labora-

tory. VCH Weinheim, N.Y.-Basel-Cambridge, 1137.

Schwertmann U. & Taylor R.M., 1989: Iron Oxides. In: Dixon J.B.

& Weed S.B. (Eds.): Minerals in soil environment. Soil Sci.

Soc. America, Madison, Wisconsin, 379438.

Schwertmann U., Fitzpatric R.W., Taylor R.M. & Lewis D.G.,

1997: The influence of aluminium on iron oxides. Part II.

Preparation and properties of Al substituted hematites. Clays

and Clay Miner., 105112.

Stumm W. & Sulzberger B., 1992: The cycling iron in natural en-

vironments: considerations based on laboratory studies of

heterogeneous redox processes. Geochim. Cosmochim. Acta,

56, 32333257.

ucha V., Kraus I., Zlocha M., Streko V., Gaparovièová M.,

Lintnerová O. & Uhlík P., 1997: Acidification in the obov

region (tiavnické vrchy Mts. Slovakia): Manifestation and

causes. Miner. slovaca, 29, 6, 407416 (in Slovak).

Thomas G.W. & Hargrove W.L., 1984: The chemistry of soil acidi-

ty. In: Adams F. (Ed.): Soil acidity and liming. Agronomy,

Madison, Wisconsin, 12, 455.

Trtíková S., Chovan M. & Kunierová M., 1996: Oxidation of py-

rite and arsenopyrite in the mining wastes (Pezinok, Malé

Karpaty Mts.). Book of abstracts of 1th. Conference of IGCP

no.405, ENVIWEATH 96, Brno, 72.

van Reeuwijk L.P: (Ed.), 1995: Procedures for soil analyses. Inter-

national soil reference and information, FAO UN, Wagenin-

gen (Netherlands).

Webster J.G., Nordstrom D.K. & Smith K.S., 1994: Transport and

natural attenuation of Cu, Zn, As and Fe in the Acid mine

Drainage of Leviathan and Bryant Creeks. In: Alpers C.N. &

Blowes D.W. (Eds.): Environmental geochemistry of sulfide

oxidation. Amer. Chem. Soc., Washington, 550, 244260.

Wieder R.K. & Novák M., 1995: Biogeochemical processes during

the treatment of acid mine drainages: The Kentucky wetland

project. In: Paava, Køíbek & ák (Eds.): Mineralium Depos.,

Balkema, Rotterdam, 709712.

Note: This paper was presented at the Conference of the IGCP Project #405 ENVIVEATH, held in Bratislava from 24th to 26th November, 1997