Mining Methods Vary Widely - Mining and the Environment: From Ore to Metal - page 226

with brine which is saturated with potassium chloride and sodium chloride. Flotation,
crystallization, or heavy media separation methods are then used to recover potassium-
bearing compounds from the saturated solution (UNEP 2001).
Worldwide potash production is dominated by Canada, Russia, and Germany, which
together account for about 76% of the total production. About one i fth of the world pot-
ash production comes from European mines in France, Germany, Spain, and the UK (EC
2004). Potassium chloride (KCl), commonly referred to as muriate of potash (MOP), is the
most common and least expensive source of potash. Potassium chloride accounts for about
95% of world potash production (EC 2004). Potash tailings are composed of table salt
(sodium chloride) together with a few per cent of other salts (e.g. chlorides and sulphates
of potassium, magnesium and calcium) and insoluble materials such as clay and anhydrite.
Dry stacking of large volumes of potash tailings (salt) on un-lined ground was historically
common practice in France and Germany and has led to large-scale ground water con-
tamination by salt (Spitz 1981, Rinaudo 2003, and Lottermoser 2007). Some potash heaps
reached 240 m in height, containing about 130 million tons of salt tailings. The tailings
heaps themselves generate saline solutions when atmospheric precipitation dissolves salt
from the tailings material (see also Case 4.7). Today, i ve methods are common for manag-
ing potash tailings, each of them having their own specii c environmental issues. These
tailings management options are: (1) storing solid tailings on tailings heaps; (2) backi ll-
ing solid tailings into mined out voids of underground workings; (3) discharging solid and
liquid tailings into the ocean/sea (e.g. marine tailings management); (4) discharging liquid
tailings into deep wells; and (5) discharging liquid tailings into natural l owing waters (e.g.
rivers) (EC 2004; UNEP 2001).

The tailings heaps generate saline
solutions when atmospheric
precipitation dissolves salt from
the tailings material.

Environmental Impacts of Mining Non-metallic Minerals
In general, mining of industrial minerals is of less environmental concern than mining
of metals or fossil fuels (see Chapter Thirteen for an overview of environmental concerns
relating to metals and coal mining). It is recognized, however, that industrial minerals
are recovered in much larger volumes, at far more locations, and in many different ways.
Some industrial minerals are sold as mined, i.e. without being processed. In other cases a
variety of mineral processing methods are applied to achieve a highly concentrated prod-
uct. The majority of mines in the industrial minerals sector use only physical treatment
(e.g. crushing, washing, magnetic separation, optical sorting, hand sorting, classii cation,
l otation, and evaporation), with only a minority of projects carrying out a chemical treat-
ment of the mineral (e.g. leaching). Industrial minerals mining operations are generally
small compared to most metal mines. The value of one unit of industrial mineral is gener-
ally lower than one unit of product from metals mining, and most industrial minerals are
only mined if they can be extracted with minimum movement of waste materials (over-
burden and waste rock). While the amounts and characteristics of tailings and waste rock
vary signii cantly, in most cases the amounts of waste rock and tailings, the areas of most
concern in metals mining, are much smaller compared to metals mining. Acid rock drain-
age is seldom an issue in the industrial minerals sector. Many other environmental issues
remain the same: land disturbance, vegetation clearing, topsoil removal, dust, erosion,
rehabilitation, and mine closure.
The building sector in particular rel ects the size of industrial minerals extraction, while
demonstrating the low value per ton of product. Most industrial minerals do not support
high transportation costs and mining of industrial minerals often occurs close to the end
users; hence most people are familiar and comfortable with this industry sector having
grown up with the familiar sight of at least one industrial mine or quarry in their extended
neighbourhood. Social issues if they occur tend to be localized, often related to land

Most industrial minerals are only
mined if they can be extracted
with minimum movement of
waste materials.