The closest "English English" equivalent of
"химико-механический завод"

See a discussion entry and the references below

If the actual expression to be translated is "химический завод" (as in the context), then it would be simply
"chemical plant"


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Note added at 15 час (2011-05-27 13:52:13 GMT)
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To be sure, you can add 'chemical' => 'chemical process equipment plant'
'chemical equipment plant' is technically fine, too

However, neither of these is standard in "English English"

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Note added at 6 дн (2011-06-02 07:03:43 GMT) Post-grading
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Any time :-)
The research was easy to do: just sit back and google "химико-механический" + a couple of carefully chosen words matching the context (I call such words 'pinpointers')

Here's an extra advice
The context of "техников-механиков химических заводов" does not seem to be associated with particular plants. If this is true, you can simply translate this word combination as
"process equipment technicians"
e.g. see
http://boise.olx.com/wet-process-equipment-technician-iid-12...