Miscellaneous Organic Chemical Manufacturing
(MON): virtual
tour
Source Category and Process Description
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 The
MON MACT will generally regulate emission sources in organic chemical
manufacturing that are not regulated under other MACT standards.
Because the MON’s compliance date is later than either the
Pharmaceutical MACT or the Pesticide MACT, it will become the “catch
all” MACT standard for miscellaneous organic chemical processes
that have not been regulated under earlier standards.
 Therefore,
an organic chemical manufacturing process that is not part of a
pharmaceutical or pesticide affected source but is located at a
major source that uses, produces, or processes HAP will most likely
be subject to the MON. The MON will also cover solvent recovery
processes and formulation processes that have previously been excluded
from other MACT standards. Examples are the Hazardous Organic NESHAP
(HON) (which excluded batch vents and sources with only HAP solvent
emissions from its affected source) and the Pesticide MACT (which
specifically excludes formulation operations).
Source Category and Process Description
 Chemical
processes vary widely from one industry to another with respect to
the types of chemicals that are used, batch and production sizes,
and unit operations that are involved. However, most chemical processes
include at least one or more combinations of four basic operations:
- Preassembly
- Reaction
- Isolation, and
- Purification.
Solvent recovery operations are also important because they enable
the chemical operator to reuse basic raw materials and reduce the
manufacturing cost and environmental impact. Additionally, cleanout
operations are important since they enable production equipment to
be reused for other manufacturing operations.
Preassembly
 
A preassembly (or premixing) is normally the initial step of the
process and typically involves charging, mixing, or dissolving
various liquids, solids, and/or gases. Essential equipment for
this step might include agitated vessels or tanks with charge chutes,
liquid inlet lines, and utility connections for temperature and
pressure control. For certain continuous chemical processes, feed
preparation might involve inline mixers with heat exchangers.
Reaction
  The
purpose of the reaction step is to facilitate the actual chemical
synthesis. A reaction may be carried out by applying heat or
by adding specific reactants to the batch. The batch composition
changes as the reaction takes place although many of the compounds
such as process solvents and other materials remain unchanged.
Equipment that is used to carry out reactions includes a batch,
semi-continuous stirred tank or tubular reactor. The actual reactor
used must meet the specific chemical, physical, and productivity
needs of the process design.
Isolation
 Once
chemical products have been formed from reaction, they must be
recovered or isolated from basic process impurities that also
formed or from unreacted materials and/or process solvents. In
many cases the product is the solid portion of a batch slurry.
Isolation can be achieved through the use of spray driers coupled
with various dust collectors. Extraction, crystallization filtration,
or distillation might be applied in cases when the batch product
is a homogeneous solution. Distillation is often used for collecting
liquid products when the vapor pressure/temperature relationships
can be exploited.
Purification
 Once
isolated, chemical products must be further processed through
purification equipment to obtain the desired high purity level.
Products from this purification step are to be used either as
the final product or as a key ingredient in the next step of
a multi-step synthesis. For example, in a pharmaceutical process
a low quality product might be purified by carbon treatment,
additional extractions, ion exchange, chromatography, or crystallization.
The overall purification process involves other preassembly,
purification, and final isolation steps.
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