Деловой английский язык. Енютина А.А. - 30 стр.

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    c) Барьер (safety wall) по краю бермы помогает удержать обломки по-
роды и направляет дождевые воды в сторону от карьера.

                                   TEST № 21

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                                  Stripping ratio

      The ratio between waste quantities and ore quantities is called stripping ra-
tio. It is controlled by economic considerations and can be used to compare dif-
ferent alternatives. There are three kinds of stripping ratios: the overall stripping
ratio, stripping ratio during a year, the incremental stripping ratio.
      The overall stripping ratio is defined as:
      Overall stripping ratio = Total waste / Total ore.
      The yearly stripping ratio in an operating mine varies from year to year and
can be found in the annual mining plans.
      The incremental stripping ratio is defined as:
      Incremental stripping ratio = Additional waste / Additional ore.
      Waste removal must often be performed many years before the correspond-
ing ore production will be reached. Waste rock therefore means that the mining
company must invest a lot of money in the mine, an investment which is hope-
fully paid back later by high revenues.
      To reduce interest cost and to maximize the profitability of expanding of
mine, it is important to delay waste stripping as long as possible. Therefore, it is
wrong to mine waste at the same time as ore mining is done at the same level
in the mine. Instead, the waste volume should be split up into several push-
backs. Waste rock within a new pushback should be started as late as possible to
save interest costs. But the waste rock must of course be removed in such a time
that ore mining at deeper and deeper benches is guaranteed.

                                     Задания

     1. Переведите текст на русский язык.
     2. Ответьте на вопросы к тексту:
     a) What is called stripping ratio?