Minerals waste

Although they are generally inert and non-hazardous, the generation and disposal of mineral wastes - and the potential for associated environmental and social impacts - can be a source of friction between aggregates companies, local communities and other stakeholders. This is particularly true if a site is producing larger amounts of waste than originally planned or that can be properly accommodated within the site boundary. Therefore, ensuring that the site design is correct at the planning stage is essential. Many of the potential impacts can be prevented or mitigated by the use of good practice. The acceptability of impacts that remain after good practice measures have been put in place should be considered in the context of the economic and other benefits that accrue from aggregates production.

What are mineral wastes?


	Mineral wastes are a largely unavoidable by-product of extraction and processing of aggregates for which no market exists. Unlike many other wastes they are generally inert and non-hazardous. Most sand and gravel workings do not produce large amounts of permanent waste, with the material that is generated being used during restoration of the site. Production of waste at hard rock quarries varies from small to large depending on the nature of the site, the depth of the saleable material and the quality of rock extracted.

Mineral wastes are a largely unavoidable by-product of the extraction and processing of aggregates. They are defined as wastes because no market exists for them, but unlike many other wastes they are generally inert and non-hazardous. Materials that may be classified as mineral wastes include:

Overburden and interburden - material of limited value that occurs above or between layers of economic aggregates.
Processing wastes - non-marketable fine grained material (often in slurry form) from screening, crushing and other processing activities.

The type and amount of waste depends on the nature of the operation. For example, most sand and gravel workings do not produce much, if any, permanent waste. Some produce significant volumes of clay and silt which in some cases can be dug from settling ponds and used during restoration. Hard rock quarries vary in the amount of waste material produced. Some may produce small amounts of overburden while others may have large amounts of overburden and material within the excavated rock (interburden) which is not of sufficient quality for the desired product. The china clay industry has particular problems with its very high level of permanent waste which it cannot return to the excavation.

Any waste that cannot be used immediately is disposed of in tips within the boundaries of the aggregates operation. The term ‘tip' is used to describe any accumulation of mineral wastes, including waste and soil heaps, stockpiled materials, backfill, screening embankments, and lagoons and settling ponds used to retain slurry from the processing plant and as such all are strictly regulated under the Quarries Regulations 1999 and the accompanying code of practice.

Mineral wastes are a largely unavoidable by-product of extraction and processing of aggregates for which no market exists. Unlike many other wastes they are generally inert and non-hazardous. Most sand and gravel workings do not produce large amounts of permanent waste, with the material that is generated being used during restoration of the site. Production of waste at hard rock quarries varies from small to large depending on the nature of the site, the depth of the saleable material and the quality of rock extracted.

Tips may be permanent or temporary. For example, permanent screening embankments (which under the Quarries Regulations 1999 are treated as tips) comprise waste or other materials not required for restoration works or other uses at a later date. They are generally designed to be incorporated into the final long-term landscape on closure and restoration of the operation. Temporary amenity banks are often formed from stockpiled topsoil and subsoil to the height of a few metres and are designed to be dug back up and used as a cover material during site restoration.

Mineral waste tips.

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