The contribution is focused on the relation between sorptive efficiency, mineral structure, and reclamation extraction of clay sorbents originating from the Most Basin. Clay sorbents are an important accessory raw material that occurs on several localities in the North Bohemian Brown Coal Basin, which are briefly described in the first part of the paper. The results from clay sorbents were obtained by mineralogy survey based on a diffract analysis with a D 5000 Siemens X-ray diffractometer. Localities, where zeolites and montmorillonites were found, are the main subjects of the research. The results show that parameters of clay sorbents mined in these localities are suitable for reclamation works. A successful reclamation with the use of bentonites is demonstrated on Strimice dump.
The Most Basin (formerly North Bohemian Brown Coal Basin) represents the largest supply of brown coal in the Czech Republic. The surface brown coal quarries caused considerable damage to the surrounding landscape. Rapid adaptation and step by step incorporation of these anthropogenic formations into territory’s ecosystem is in the interest of both the region’s inhabitants and the mining companies. Successful reclamation works require fertilization of sterile and phyto-toxic sites. Natural clayey sorbents are possible solution in this case. Clays are often used in agricultural applications, in engineering and construction applications, in environmental remediations, in geology and in many other miscellaneous applications [
The geological situation of both large brown coal basins is rewiewed in this chapter in relation to the presumed occurrence of claystone sorbents. The research of the characteristics of the rocks was commenced in four current mining localities. These were the Bílina, Libous, Vrsany, and CSA mines. The characteristics of the stratigraphic situation are set out here with respect to the reclamation utility and potential occurrence of claystone sorbents. In the recultivation, there are easily usable quarter rocks in the Bilina mine area (topsoil, loess and loess loams are selectivelly mined and used as fertilizable rocks) and grey kaolinite―the illite claystone of Libkovice strata, which forms the upper horizon of tertiary [
A potential sorbent usable for reclamation works in the region of the North Bohemian Basin is the caolinitic-illitic claystone of the overburden Libkovice strata of the Bílina mine (limited utility), the montmorillonitic overburden claystone of the Libous mine and the bentonites of the Cerný vrch and Rokle localities. Just out of intrest, numerous deposits of zeolites in nearby Ceské Stredohorí Mountains can also be mentioned. These have great mineralogic significance, but none of them has the character of a minable locality according to contemporary economic criteria. The localities are usually active quarries, where appropriate vulcanite is the utility mineral and zeolite mining is economically impossible.
They form the upper horizon of the tertiary level in the Bílina mine. This rock type consists mainly of clays, and claystone to dusty claystone of brown to grey-brown colour. It is fine-grained, and its mineralogic complexion is dominated by quartz, caolinite, and illite. They have very good chemic-pedologic qualities. Their sorption abilities can be marked as medium. They can be immediately used for forest reclamation; a systematic areal compost application is recommended.
They appear at the top horizon of the tertiary level under yellow clays. This rock type consists mainly of clays, and claystone to dusty claystone of brown, yellow-brown to grey-brown colour. It is fine-grained, and its mineralogic complexion is dominated by quartz, montmorillonite, caolinite, illite, and traces of feldspar. They have very good chemical-pedologic qualities. Their sorption abilities can be described as excellent. They can be immediately used for forest reclamation. A compost or industry fertiliser application to single plants is recommended.
The only significant deposits of bentonite in the North Bohemian Basin are concentrated in the vicinity of Branany village (Cerný vrch hill locality) and in Kadan town (Rokle locality). Bentonites can be defined as montmorillonite claystone. It is fine-grained, with its mineralogic complexion dominated by montmorillonite; caolinite and quartz are normal ingredients, with some traces of illite, siderite, and feldspar. They have excellent chemical and pedological qualities and very high sorption ability, and their reclamation utility is excellent. Application in large reclamation actions is limited by its economic demands.
The Cerny vrch bentonite locality can be found about 1 km from classic recently mined Branany deposit. Together with Rokle near Kadan town, they are the most significant deposits in the Most Basin today. The locality is bound to the vulcanodetritic strata of the coal seam subjacent bed. It consists mainly of clayed tuffs; a marginal eroded vulcanic rock was the mother rock. High quality blue to blue-green betonite occurs in the deposit (especially in its base). Most of the deposit consists of yellow-green to yellow-brown bentonite. The raw material can be used as bleaching clay (the best quality bentonite) and foundry purposes; recently it has also been used in the production of cat litter. The Cerný vrch deposit verges into the Strimice deposit, and the mined locality is usually referred to as Cerný vrch by the owner (Keramost, j.s.c.). The mined bentonites consist of montmorillonite, with the main ingredients being caolinite, siderite, illite. Quartz can also occur in a lower rate. The situation in the locality is shown in
The second most important bentonite deposit, in Rokle is about 3 km south at Kadan town near the slopes of the Doupov Mountains (
The locality is linked to the tertiary vulcanodetritic strata of the coal seam subjacent bed. It consists of sandy tuffitic tuffs. All the pyroclastic material except biotite is totaly dispersed in the clayey mass. Most of the deposit consists of yellow-green to yellow-brown bentonite. The raw material can mainly be used for foundry purposes. A horizon of caolinic sands, approximately 5 to 10 m high, can be found under the bentonite horizon, approximately 30 m high; these are also mined as raw kaoline. The mined bentonite consists of a mixture of the prevailing montmorillonite and caolinite, with the main ingredients being siderite, illite and quarty. The raw material is of a slightly lower quality than that in the Cerný vrch locality. The quality of the bentonites in the Cerný vrch and Rokle localities is shown in
| locality of bentonite sample | N (%) | Cox (%) | CaCO3 (%) | pH/H2O | Receivable nutrients (mg∙kg−1) | Absorbtion Capacity mmol (%) | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| P | K | Mg | S | T | V | |||||
| Cerny vrch | 0.05 | 0.53 | 8.86 | 8.31 | 2 | 321 | 998 | 38 | 38 | 100 |
| Rokle | 0.05 | 1.07 | 5.65 | 7.99 | 1 | 288 | 876 | 24 | 24 | 100 |
Dump (spoil tip) is an anthropogenic formation made of overburden soil that cover coal seam. The Strimice dump is located near the town of Most. It had been formed since 1959 to 1973 and its elevation point reached 330 meters above sea level. Bentonite rocks that were mined in Cerny vrch were used for creation of a 50 cm thick surface layer. After the ploughing, grass and trees were planted on the dump. 89 ha of the dump surface were then used for agricultural reclamation [
| Probe S1-sample taking interval (m) | N | Cox | CaCO3 | pH/H2O | Receivable nutrients (mg∙kg−1) | Absorbtion Capacity mmol (%) | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| (%) | (%) | (%) | P | K | Mg | S | T | V | ||
| 0.00 - 0.60 | 0.07 | 1.24 | 0.98 | 6.79 | 10 | 190 | 102 | 13.4 | 19.7 | 68 |
| 0.60 - 0.90 | 0.07 | 0.68 | 9.93 | 8.23 | 1 | 218 | 949 | 36.3 | 36.3 | 100 |
| Under 0.90 | 0.15 | 2.94 | 0.24 | 4.50 | 1 | 103 | 304 | 3.1 | 8.2 | 39 |
of clay and bentonite and the original material in the dump. Mineralogy of upper layer is defined by quartz, kaolinite, illite, and montmorillonite with a mixture of spars and muscovite. The chemical status of the upper relatively favourable with neutral soil reaction, medium content of humus, low content of nitrogen and phosphorus, and medium to high content of magnesium and potassium. The soil is quite coarse, and sandy to loamy, therefore it is suitable for reclamation. The middle layer contains larger amount of montmorillonite. The soil reaction is lightly alkaline with increasing calcite content. The nitrogen and humus content is low. Middle layer is a bit higher on nutrients than the upper layer. This soil is not suitable for reclamation, because it contains yellow clay with pieces of coal. The results shown in
The potential deposits of claystone sorbents in the North Bohemian Basin will be found and evaluated in the frame of the recently commenced research works. These rocks would otherwise end up in mine dumps, but nevertheless they may sometimes be raw materials with exceptional qualities. A suitable application of claystone sorbents will make the technical restoration in the North Bohemian Basin more effective and it can also be used in the sanitation of the old ecologic burdens in the Czech Republic (especially in the cases of involving contaminated mine waters). The kaolinite-illite claystone of the Libkovice strata, motnorillonite claystones and bentonites were tipped as potential claystone sorbents in the first stage of the mapping works. The occurrence of these rocks, their brief characteristics, and their application possibilities in the reclamation are described in the article. The experiences from the single large application of claystone sorbent in the Strimice dump so far are also set out here.
This article was supported by project QJ1520307 entitled “Sustainable Forms of Management in an Anthropogenically Burdened Region”. This project was realized with financial support from state budget resources through the KUS program, Ministry of Agriculture of the Czech Republic.
Řehoř, M., Vráblík, P., Vráblíková, J. and Žižka, L. (2017) Sorbent Mineralogy in the Most Basin and Their Utilization for Reclamation Works. Open Journal of Geology, 7, 1767-1773. https://doi.org/10.4236/ojg.2017.712118