Formation of some manganese minerals from ferromanganese factory waste disposed in the Krka River Estuary

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00,13-1354(95)00207-3

Brat. Res. Vol. 30, No. 3, pp. 495-500, 1996 Copyright © 1996ElsevierScienceLtd Printed in Great Britain.All rights reserved 0043-1354/96$15.00+ 0.00

FORMATION OF SOME M A N G A N E S E MINERALS FROM F E R R O M A N G A N E S E FACTORY WASTE DISPOSED IN THE KRKA RIVER ESTUARY HALKA BILINSKP*, ~ELJKO KWOKAL 2 and MARKO BRANICA 2 ~Department of Physical Chemistry and 2Center for Marine Research Zagreb, Ruder Bo~kovi6 Institute, POB 1016 10000, Zagreb, Croatia (First received March 1995; accepted in revised form August 1995) Abstract--The identification, characterisation and formation of manganese minerals takanelite and kutnahorite calcian found in the Krka River Estuary, is described. These minerals originated from the hydrochemical transformation of waste disposed from a ferromanganese factory. Industrial slag, dust settled inside a chimney, and marine sediments in the vicinity of the ferromanganese plant "Crnica", situated in the suburb of the city of ~ibenik were analysed in details. The samples of slag and dust were equilibrated with estuarine waters for 20 d. In marine sediment, calcite is predominant, while quartz, aragonite, kutnahorite calcian and dolomite were found as minor components. Iron is present in all samples as an amorphous phase. Strontium, titanium, copper, zinc, lead and rubidium were found as microcomponents. It was found that slag and dust particles partly dissolvein contact with estuarine water of different salinities, and present renewable supply of manganese, iron and numerous trace elements. A possible way of the formation of manganese minerals takanelite and kutnahorite is discussed. Takanelite mineral was obtained in laboratory by partial disolution of slag containing bustamite ferroan. For kutnahorite calcian it is suggested that it forms in the process of dolomitization. With respect to aqueous environment of the Krka River Estuary, the slag and dust from a ferromanganese industry upon contact with water transform into scavengers (gypsum, calcite, quartz, takanelite) which help purifying the water column from other micro-impurities. Key words--feromanganese industry, Krka River Estuary, waste transformation, manganese, iron, takanelite, kutnahorite calcian, calcium manganate, bustamite ferroan, braunite

INTRODUCTION The city of Sibenik, situated at the mouth of the Krka River Estuary, is seasonally polluted by gases CO2, CO, SO2, manganese and carbon dust from a ferromanganese industry and also by gases SiF4, CF4, HF, CO2 and SO2 from an aluminium industry. The polluted regions have been described in the local report in which the necessity of preventing further air pollution was strongly suggested. Such a polluted atmosphere is harmful not only to cultural monuments, plants and animals, but especially to children and old people in this region (Sekulir, 1986). Industrial slag is spread around the ferromanganese factory. It comes into direct contact with rain and in some places with estuarine water. In spite of these pollution-occurring facts, the Krka River Estuary which is partly located within a National Park, represents one of the most pristine rivers in Croatia. Numerous field studies (Branica et al., 1985; Prohi~ and Jura~ir, 1989; Martinri6 et al., 1989; Mikac et al., 1989; Bilinski et al., 1992) show that trace metal concentrations in the whole aquatorium are very low. From model adsorption experiments, it *Author to whom all correspondence should be addressed.

was concluded that calcite mineral contributes to the self-purification mechanism (Bilinski et al., 1991; Kozar et al., 1992). This paper describes chemical and mineralogical composition of industrial slag and dust from a chimney of a ferromanganese factory, as well as their transformations in the contact with estuarine water. Our attention is focused on major minerals and trace elements in recent sediments in the vicinity of the factory, with special emphasis on manganese minerals. Taking into account our measurements, and the results recently published from Pinal Creek, Arizona (Lind and Hem, 1993), we try to understand which kind of natural processes masters the uncontrolled anthropogenic input of manganese and trace elements into the Krka River Estuary. EXPERIMENTAL Sampling The map illustrating the Krka River Estuary and the sampling stations is presented in Fig. 1. The Krka River Estuary, belonging to the type of karstic estuaries, is located in the central part of the eastern Adriatic coast of Croatia. It is characterized by a close interactions of hydrometeorological phenomena, underground karstic waters and nearshore saline waters. The total length of the

495

496

Halka Bilinski et al.

•

ILl

% Fig. 1. The map of the Krka River Estuary.

Krka River Estuary is 22 km. The depth of the estuary gradually increases from 2 m (at the falls) to 42 m on the seaward side, at the end of the Sibenik channel. The main water supplier is the Krka River with an average freshwater inflow of 55 m3s ~, and considerable seasonal and monthly variations, ranging from 10 to 400 m3s ~. Due to its sheltered geography and comparatively low tidal range (0.2-0.5 m) the Krka River Estuary is classified as a highly stratified type of estuary. Sample numbers and the kind of samples are presented in Table 1 of the results. We have obtained samples Nos 0, 4 and 5, courtesy of the authorities of the ferromanganese factory. Sample No. 1 was collected at the coast near E-5 station, where industrial slag is deposited and becomes exposed to rain water. Samples Nos 2 and 3 were collected at the coastal slope just in front of the ferromanganese factory. The difference between them is that sample No. 3 was taken at the depth of about 9 m bellow the surface of the sea, while sample No. 2 was above it, and becomes exposed to rainwater only. Marine sediment samples (Nos 6 and 7) were collected from station E-4 (at the depth of 22 m and 15 m, respectively) by a diver using an acrylic glass tube (20 cm long and 6 cm i.d. The tube was inserted into the seabed for its total length, and plugged with a polyethylene stopper. Model dissolution experiments of the collected samples of industrial slag and dust from the chimney, were performed

with natural estuarine water (station E-2) taken at three depths 4.70, 4.80 and 4.89 m, with salinities of 2, 26 and 37%, respectively. Instruments and procedures

Mineralogical composition of all solid samples was determined by an X-ray diffractometer and proportional counter (Philips, PW 1050, X-ray diffractometer) with CuKc~ radiation. Crystalline phases have been identified using a Powder Diffraction File (Powder Diffraction File, International Centre for Diffraction Data, Swarthmore, PA., U.S.A.). Elemental analysis was performed by X-ray fluorescence spectroscopy (Philips Roentgen Apparatus, Model PW 1010/30) according to Valkovi6 et al. (1984). Elements lower than phosphorus in periodic system could not be measured. Model partial dissolution experiment of slag and dust particles in estuarine water from station E-2, was performed in laboratory (using approx. 2 gl-t alter 20 d of equilibration at room temperature). After filtration through Millipore filter (0.45/am), solid phases have been collected, dried and characterised mineralogically. In the remaining solution, analysis of soluble manganese ion was performed by Jarrel-Ash 82271 atomic spectrophotometer. Calcium and magnesium concentrations were measured complexometrically with Titriplex III using an Indicator

Manganese minerals in the Krka River Estuary

497

Table 1. Mineralogical composition of solid samples from the area of a ferromanganese factory (gibenik, Croatia) Sample No. Kind of sample 0 Orea 1 2

3

4 5 6a 6b

Major minerals Mn~.sFe~25Ca0.~Ba0.~Sio.4~Oi2, braunite (19-180)

CaMnO3, calcium manganate (3-830) Slag coast E-5 station July, 1992 CaMnO3, calcium manganate (3-830) Slag coastal slope in front of ~t-SiO2, quartz (5-0494) ferromanganese factory above seawater surface August, 1994 CaCO3, calcite (5-586) ~-SiO2, quartz (5-0494) Slag coastal slope in front of ferromanganese factory 9 m below seawater surface (Ca, Mn)3 Si309, bustamite ferroan (33-292) Slag~ from the factory C, graphite (23-64) Dusta from the factory MnO, manganosite (7-230) CaCOj, calcite (5-586) Marinesediment ~t-SiO2,quartz (5-0494) E-4 station depth 22 m l cm 13 cm July, 1992 CaCO3, calcite (5-586)

Marinesediment E-4 station depth 15 m August, 1994 CaCO3, calcite (5-586) aCourtesy of the ferromanganese factory. ( ) Ref. No. in powder diffraction file.

Minor minerals (Li, AI) Mn:O4, lithium, aluminium manganese oxide (15-608) --

CaMnO3, calcium manganate (3-830)

(Ca, Mn)3 Si309, bustamite (26-1066) MnFe204, jacobsite (10-319) Ca074 (Mn, Mg)026CO3, kutnahorite calcian (19-234) CaCO3, aragonite (5-453) Ca07a (Mn, Mg)0.26COj, kutnahorite calcian (19-234) CaCO3, aragonite (5-453) ~t-SiO2,quartz (5-0494) CaCO3 MgCO3, dolomite (I 1-78)

7

Buffer Tablet (Merck). Calcium concentration was determined separately using an indicator Murexide. Magnesium ion concentration was calculated from the difference of the two last measurements. RESULTS

Mineralogical and chemical characterisation of sampled slag, dust and sediment materials In the ferromanganese factory the production of a M n (32-637) and of ~Fe (6-696) is going on, using the ore characterised as a mineral braunite (19-180). In the technological process limestone and coke are also used. Mineralogical composition of the ore (sample No. 0) and of selected slug, dust and sediments samples is presented in Table 1. Two different types o f slag materials were collected Nos 1, 2, 3 and No.4. The first group of slag is mainly composed of calcium manganate, CaMnO3 (3-830). Sample No. 4 represents the other slag type. It is mainly composed of bustamite ferroan (33-292). Sample No. 5 is poorly crystalline dust coming from the furnace. It is mainly composed of carbon (23-64) of manganese(II) iron(III) oxide (38-430) and of manganese(II) oxide (7-230). By Coulter counter measurement it was found that dust particles are of fine size, bellow 2 # m in diameter. Although human exposure in this region was previously studied (~ari~ et al., 1975) and is out of the

CaCO3, aragonite (5-453) ct-SiO2,quartz (5-0494)

scope of this work, we would like to direct attention to air pollution. When inhaled, dust particles may be deposited into the human lungs, remain there for weeks, months or even longer, causing respiratory and other diseases. The details are reviewed in the E P A Health Assessment Document for Manganese, 1984. Samples No. 6 and 7 are marine sediment samples taken in the vicinity of the factory, with the aim to identify in them manganese mineral, which is a possible sink for manganese in the Krka River Estuary. Although sample No. 7 was taken at a depth of 15 m and sample No. 6 at a depth of 22 m, which is further from the factory, none of the manganese minerals could be identified in the closer sample. After the acid dissolution of calcium carbonate in sample No. 7, in the dark grey residue only silica, SiO2 (12-708) was identified. A single additional peak at d = 3.24 could not as yet be assigned. In the sediment sample No. 6, the surface layer at 1 cm (No.6a) and deeper layer at 13 cm (No. 6b) of the same core were analysed. In both cases manganese mineral identified was kutnahorite calcian, Ca0.74 (Mn, Mg)0.26CO3 (19-234). In the deeper layer, there is an evidence of dolomite (11-78) formation. The formation of kutnahorite mineral in the Krka River Estuary sediments in which dolomitization proceeded, could be expected. Namely, calcite shows a very limited ionic substitution by Mg, Fe and Mn,

H a l k a Bilinski et al.

498

Table 2. Results of X-ray fluorescence analysis" of solid samples (Sample No. corresponds to Table 1). Major components are presented in % and traces in fig/g Sample No.

P (%)

S (%)

K (%)

Ca (%)

1 2 3 4 5 6a 6b 7

0.21

1.19

1.74 --

0.15 1.07

2.00 15.11 1.75 7.15 1.91 10.43 0.92 12.40 3.98 4.50 0.61 11.80 0.65 14.40 3.59 22.85

Mn (%) 8.50 15.20 12.56 21.00 30.05 8.90 6.50 1.31

Fe Ti V Ni Cu Zn As Br Rb Sr Y Au Pb U (%) (fig/g) (fig/g) (fig/g) (fig/g) (fig/g) (fig/g) (#g/g) (fig/g) (fig/g) (fig/g) (fig/g) (fig/g) (fig/g) 0.03 3.64 2.26 0.34 5.20 2.30 1.80 1.02

1220 191 1284 2690 1362 2310 168 69 25 - 238 35 275 110 59 395

-99 138 14 69 16 7

33 272 230 43 288 303 255 577

59 278 882 23 3018 1557 1541 265

9 50 107 18 78 180 213 --

--20 --230 187 105

20 60 52 11 92 42 29 14

4958 4370 3835 4033 1018 1978 2640 3269

99 93 78 39 5

33 --52 82

--

--

3 89 132 -631 1943 1922 138

---54 -----

•Elements lower than P in Periodic System could not be measured. (--)Below detection limit.

while it is known that a complete solid solution exists between dolomite and ankerite + kutnahorite (Manual of Mineralogy, 1985 ). Iron minerals could not be identified in the sediments. Table 2 contains the results of the element analyses of the samples Nos 1-7 from Table 1. Concentrations of macroelements are given in % and of micro elements in #g/g. From macro elements, calcium and manganese are the most abundant in all samples. Magnesium was analysed only in the sediment samples. Sample No. 6a contained 3.42% and sample No. 7 contained 1.19% of the total magnesium ion. The concentration of potassium is relatively high in slag and dust samples, and also in the sediment samples closer to the factory (sample No. 7). The concentration of iron is the highest in dust (sample No. 5). Strontium, titanium, copper, zinc, lead and rubidium are found as micro components in all samples. Nickel and arsenic are found in most samples. Bromine was found in slag exposed to sea water (No. 3) and in sediments (Nos 6a, 6b and 7). Ytrium, gold and uranium were not detected in sediments, suggesting their possible stability in the water reservoir.

Model dissolution experiments

Samples Nos 1, 4 and 5 have been equilibrated in laboratory with estuarine waters for 20 d. After the removal of solid phases, the concentrations of manganese, calcium and magnesium ions were determined in the solution. It was observed that Mn 2+ concentration increased with salinity (4-17 mg 1-~) and Ca 2÷, Mg 2+ concentrations slightly decreased in comparison with original estuarine waters. These data can be considered as qualitative ones. The mineralogical composition of the remaining solids shows partial transformation of phases as presented in Part A of Table 3. At the salinity of sea water, slag (No.l) is partly dissolved followed by the formation of gypsum (33-311). For this phase it is known that it adsorbs organic anions and organic cations, presumably at different sites (Orenberg et al., 1985) and thus can add to the self purification of aquatic environment. In natural sediments of the Krka River Estuary there is as yet no evidence of gypsum formation. Upon ageing of slag No. 4 in sea water, in addition to its major component bustamite ferroan (33-292), calcite (5-586), takanelite (25-164) and g-SiO2

Table 3. Distribution of minerals at estuarine station E-2 and after laboratory experiments

Sample 1 Slag from coast E-5 station 5 Dust from the factory 4 Slag from the factory

(A) Minerals in transformed solid phase after equilibration in laboratory with estuarine waters Estuarine water E-2 station S%o Major minerals Minor minerals 2 26 37 2 26 37 37

CaMnO3, calcium manganate (3-830) CaMnO3, calcium manganate (3-830) CaSO,.2HzO, gypsum (33-311)

Not identified white precipitate CaMnO3, calcium manganate (3-380)

Poorly crystalline, not identified

CaCO~, calcite (5-586)

(Ca,Mn)3 Si309, bustamite ferroan (33-292) (Mn,Ca)Mn409.3H20, takanelite (25-164) ~-SiO2 (5-0494)

(B) Minerals found in the water column at E-2, Dec. 1990 (Bilinski et al., 1992) Suspended matter E-2 station dffi 2.90m

26

6CaO.3SiO2.H20, calcium silicate hydrate (14-35) (Mn,Ca)Mn4Og.3H20, takanelite (25-164)

CaCO~, calcite (5-586) c~-SiO2, quartz (5-0494)

Suspended matter E-2 station d = 3.80 m Dec., 1990

37

CaCO~, calcite (5-586) (Mn,Ca)Mn,Og.3H20, takanelite (25-164)

a-SiO2, quartz (5-0494)

Manganese minerals in the Krka River Estuary (5-0494) were also formed. The last result confirms our earlier suggestion that the takanelite mineral which we found at E-2 station on the occasion (Bilinski et al., 1992), must be connected with the ferromanganese industry waste disposal. In Part B of Table 3, minerals found in suspended matter in the water column are illustrated.

Possible way o f manganese mineral formation

Comparing the results recently published, dealing with the same manganese mineral formation in Pinal Creek, Arizona, U.S.A. (Lind and Hem, 1993; Hem and Lind, 1994), we suggest a possible way in the Krka River Estuary, accordingly. Slag and dust from a ferromanganese factory situated in the city of Sibenik, are partially soluble in estuarine water, thus presenting a renewable supply of the dissolved manganese ions. None of crystalline iron phases could be found in sediments (Nos 6a, 6b and 7). We assume that iron is present as amorphous Fe(OH)3. A number of equilibrium constants and concentrations of some ions should be considered in order to understand the manganese cycling in the Krka River Estuary. The thermodynamic stability data for the takanelite formation are still not available as quoted in Hem and Lind (1994), while for kutnahorite two different values were reported (Garrels et al., 1969; Mucci, 1991). The measurements of manganese and iron concentrations in the Krka River Estuary are practically non-existing, while the concentrations of calcium, magnesium ions and pH have been reported (Bilinski et al., 1992). Recently published values for the dissolved oxygen show that the concentration decreases with the depth and that the distribution depends on the season. Higher oxygen concentrations performed in 1989 at E-4, were observed during the summer (Legovi6 et al., 1994). One could propose the reaction pathways in the manganese minerals formation from the dissolved slag and dust giving Mn 2÷ ions. Takanelite (Mn,Ca) M n 4 O g . 3H20 formation can be described using equations (1)-(3) from Lind and Hem (1993), and already known literature data quoted in Mellor (1974) as follows:

(5)

(tetrapermanganite formation) H2Mn4Og'3H~O + ~Mn 2 2+ + ~Ca l 2+ 2+ 2+ ~(Mn2,,Cam)MmO9 3H20 + 2H + (6)

The process given by equation (1) seems to occur in summer, since the oxidation is favoured by increasing the dissolved oxygen activity and raising the pH, that has been observed in the same river (Legovi6 et al., 1994). Takanelite has been found on occasion in December 1990, at station E-2 only at freshwater-sea water interface and below it (see Part B, Table 3), where it was presumably brought by currents. Preliminary measurements of 7Be radioactivity have suggested that the time for seawater to reach E-2 station in the Skradin area is ~ 150 d (Martin J.-M., personal communication). Reported calculation of the exchange time of freshwater and sea water shows 50--100 d during winter and up to 250 d during summer (Legovir, 1991). The other manganese mineral found by us in the Krka River Estuary, and described in this work, kutnahorite calcian probably does not form directly from the solution by the reaction of Mn 2+ ion and calcite as suggested (Lind and Hem, 1993) according to the reaction: yCaCO3 + xMn 2+ = Cay_ ~Mn~CO~ + xCa 2+ (7) We suggest that in the Krka River Estuary slow dolomite formation takes place in sediments by the process as described elsewhere (Boer, 1977) and that kutnahorite calcian forms by solid-state diffusion of Mn 2÷ ion to dolomite occupying Mg 2+ sites. Namely, kutnahorite calcian was not found in the sample No. 7 containing less Mg 2+ ions as compared to the sample No. 6. As a complete solid solution seems to exist between dolomite and ankerite + kutnahorite (Manual of Mineralogy), manganese and iron ions coming from slag and dust of a ferromanganese plant both can be buried into sediments by the dolomitization process. From all elements coming into the estuary with dust and slag, only ytrium, gold and uranium were not detected in sediments. CONCLUSIONS

(2)

(conversion of hausmannite to manganite) 2MnOOH + 2H ÷ ~ MnO2 + 2H20 + Mn 2÷ (3) (manganite disproportionation) MnO2 + H20 --* H2MnO3

4H2MnO3 -~ HEMIhOg'3H20

(1)

(formation of hausmannite) 2MnOOH + 2H ÷ ~ 2MnOOH + Mn 2÷

(perrnanganous acid)

(takanelite mineral formation)

DISCUSSION

3Mn 2÷ + ½02aq"~- 3H20 ~ Mn304 + 6H +

499

(4)

The major contamination source, a ferromanganese industry, at the mouth of the Krka River presents a renewable supply of manganese, iron and numerous trace elements in the surrounding environment. Industrial dust particles are of fine size ( < 2 pm) and as such can be harmful for the human respiratory system.

500

Halka Bilinski et al.

Industrial slug and dust particles partly dissolve when they get into the contact with the estuarine water of different salinities. Partial transformation of solids takes place. Some new phases are formed which are known to act as scavengers for many trace elements. Takanelite mineral was obtained by model dissolution experiment from slag mainly composed of bustamite ferroan. In addition to manganese mineral takanelite found in the suspended matter, kutnahorite calcian was found in some marine sediments. Possible mechanism for the manganese minerals formation in the Krka River Estuary is suggested. Manganese, iron, potassium and most of the trace metals can be brought into calcareous sediments. Only ytrium, gold and u r a n i u m seem to remain dissolved in the water column, as they were not detected in the sediments. With respect to aqueous environment of the Krka River Estuary, the slag and dust from a ferromanganese industry transform into good scavengers and help to purify the water from other impurities. The results presented in this work show that red water found at the freshwater-sea water interface originates on occasion from manganese mineral takanelite. Its origin due to red algae Gonyaulax polyedra Stein (GP) described in Legovi6 et al. (1991) is not the only explanation. Acknowledgements--The work was supported by the

Ministry of Science and Technology of the Republic of Croatia, and by the U.S. Geological Survey U.S.A.-Croatia joint project V, No. JF 169. We thank Mrs Moira Spanovi6 for correcting the English and typing the manuscript. REFERENCES

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