1430 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
(and incremental ash level). By operating both circuits at
1.55 RD, then near identical incremental qualities would
be obtained in both dense medium circuits. Operation at
1.55 RD provides the following total clean coal tonnage
and ash:
• Clean Coal Production =150(0.628)+350(0.742)
=353.9 tph
• Clean Coal Ash =[150(0.628)(10.8)+350(0.742)
(5.6)]/353.9 =7.0%
If instead the plant had chosen to keep running at a con-
stant 7.0% ash, which required different RD cutpoints for
each circuit, then the clean tonnage and ash would have
been:
• Clean Coal Production =150(0.389)+350(0.773)
=328.9 tph
• Clean Coal Ash =[150(0.389)(7.0)+350(0.773)
(7.0)]/328.9 =7.0%
These calculations show that the plant would gain 25 tph
without impacting clean coal quality simply by maintain-
ing the same RD cutpoint in both cleaning circuits. At an
estimated market price of $120 per tonne for clean coal,
then the net value of this improvement would be worth
$18 million annually (25 tph × $120/t × 6,000 hr/yr =$18
million). The large financial impact represented by this case
study illustrates why it is so important for plant operators to
make use of the incremental quality optimization concept.
It must be mentioned that where multiple operations
source the same sales contracts all plants should be set to
produce the same incremental (and not total) ash.
Blending can be performed to ensure customer speci-
fications are met.
ESTABLISHMENT OF BEST OPERATIONS
&MAINTENANCE PRACTICES
Major efficiency losses occur in CPPs when sizing, cleaning
or dewatering equipment is poorly designed, improperly
operated or inadequately maintained. As such, peak levels
of plant efficiency can only be sustained over the long term
through the active utilization of standardized “best operat-
ing practices” that use the wealth of knowledge t available
across an entire company. According to DePasquale et al
(2011), an effective best practices initiative should include
sequential phases of (i) development, (ii) implementation
and (iii) auditing. During development, knowledgeable
teams need to be established to develop written operat-
ing and maintenance protocols for all the major process-
ing plant equipment. Protocols should also be developed
for plant data reporting and efficiency sampling. The teams
need to include key plant personnel from management,
operations and engineering as well as input from external
experts.
Once compiled, the best practices need to be distrib-
uted across the organization. This rollout should include
initial training sessions to familiarize personnel with the
best practices and to solicit input for further improve-
ments/revisions. Ultimately, a handbook of standardized
best practices should be provided to all employees involved
in plant operations. Annual retraining should be considered
as part of an ongoing continuous improvement program.
Finally, external audits to evaluate compliance with the
best practices need to be performed on a routine basis (at
least annually). To ensure a uniform assessment procedure is
followed, a “score card” can be prepared that assigns points
for each area of best practices compliance. A common indi-
vidual should typically be included on each audit team to
ensure the same standards are applied at each plant site. The
plant manager should also provide the necessary proof, in
the form of written documents, that standards have been
met. After meeting with the plant management to review
the audit findings, a remediation plan should then be devel-
oped by plant personnel to deal with any deficiencies iden-
tified. Typically, senior corporate management will receive
the findings of the audits and the proposed game plan of
the plant manager to rectify shortcomings.
Best practice initiatives developed under the direction
of the author have confirmed the value of this approach
and its role in the continuous improvement of coal prepa-
ration facilities. For example, Figure 4 shows the annual
compliance scores for five different preparation plants over
a three-year period. From this it can be seen that there was
a steady increase in audit compliance each cycle, albeit from
an already good starting base of 90% initial compliance.
Associated economic evaluations indicated a sustained
annual gain of more than 300,000 tonnes of recoverable
coal at these sites, which can be largely attributed to the
steadily growing level of compliance with established plant
best practices and corresponding improvements in plant
efficiency and runtime. The audit process also provides an
excellent opportunity for cross-fertilization of ideas, know-
how and exposure to new innovations as each audit team
visits new plant sites.
CIRCUITY IMPROVEMENT BASED ON
NEW TECHNOLOGY
=Another key area for improving profitability is the utili-
zation of new technology to replace older low-efficiency
separators. Numerous examples exist in the technical lit-
erature documenting the large economic payback for these
(and incremental ash level). By operating both circuits at
1.55 RD, then near identical incremental qualities would
be obtained in both dense medium circuits. Operation at
1.55 RD provides the following total clean coal tonnage
and ash:
• Clean Coal Production =150(0.628)+350(0.742)
=353.9 tph
• Clean Coal Ash =[150(0.628)(10.8)+350(0.742)
(5.6)]/353.9 =7.0%
If instead the plant had chosen to keep running at a con-
stant 7.0% ash, which required different RD cutpoints for
each circuit, then the clean tonnage and ash would have
been:
• Clean Coal Production =150(0.389)+350(0.773)
=328.9 tph
• Clean Coal Ash =[150(0.389)(7.0)+350(0.773)
(7.0)]/328.9 =7.0%
These calculations show that the plant would gain 25 tph
without impacting clean coal quality simply by maintain-
ing the same RD cutpoint in both cleaning circuits. At an
estimated market price of $120 per tonne for clean coal,
then the net value of this improvement would be worth
$18 million annually (25 tph × $120/t × 6,000 hr/yr =$18
million). The large financial impact represented by this case
study illustrates why it is so important for plant operators to
make use of the incremental quality optimization concept.
It must be mentioned that where multiple operations
source the same sales contracts all plants should be set to
produce the same incremental (and not total) ash.
Blending can be performed to ensure customer speci-
fications are met.
ESTABLISHMENT OF BEST OPERATIONS
&MAINTENANCE PRACTICES
Major efficiency losses occur in CPPs when sizing, cleaning
or dewatering equipment is poorly designed, improperly
operated or inadequately maintained. As such, peak levels
of plant efficiency can only be sustained over the long term
through the active utilization of standardized “best operat-
ing practices” that use the wealth of knowledge t available
across an entire company. According to DePasquale et al
(2011), an effective best practices initiative should include
sequential phases of (i) development, (ii) implementation
and (iii) auditing. During development, knowledgeable
teams need to be established to develop written operat-
ing and maintenance protocols for all the major process-
ing plant equipment. Protocols should also be developed
for plant data reporting and efficiency sampling. The teams
need to include key plant personnel from management,
operations and engineering as well as input from external
experts.
Once compiled, the best practices need to be distrib-
uted across the organization. This rollout should include
initial training sessions to familiarize personnel with the
best practices and to solicit input for further improve-
ments/revisions. Ultimately, a handbook of standardized
best practices should be provided to all employees involved
in plant operations. Annual retraining should be considered
as part of an ongoing continuous improvement program.
Finally, external audits to evaluate compliance with the
best practices need to be performed on a routine basis (at
least annually). To ensure a uniform assessment procedure is
followed, a “score card” can be prepared that assigns points
for each area of best practices compliance. A common indi-
vidual should typically be included on each audit team to
ensure the same standards are applied at each plant site. The
plant manager should also provide the necessary proof, in
the form of written documents, that standards have been
met. After meeting with the plant management to review
the audit findings, a remediation plan should then be devel-
oped by plant personnel to deal with any deficiencies iden-
tified. Typically, senior corporate management will receive
the findings of the audits and the proposed game plan of
the plant manager to rectify shortcomings.
Best practice initiatives developed under the direction
of the author have confirmed the value of this approach
and its role in the continuous improvement of coal prepa-
ration facilities. For example, Figure 4 shows the annual
compliance scores for five different preparation plants over
a three-year period. From this it can be seen that there was
a steady increase in audit compliance each cycle, albeit from
an already good starting base of 90% initial compliance.
Associated economic evaluations indicated a sustained
annual gain of more than 300,000 tonnes of recoverable
coal at these sites, which can be largely attributed to the
steadily growing level of compliance with established plant
best practices and corresponding improvements in plant
efficiency and runtime. The audit process also provides an
excellent opportunity for cross-fertilization of ideas, know-
how and exposure to new innovations as each audit team
visits new plant sites.
CIRCUITY IMPROVEMENT BASED ON
NEW TECHNOLOGY
=Another key area for improving profitability is the utili-
zation of new technology to replace older low-efficiency
separators. Numerous examples exist in the technical lit-
erature documenting the large economic payback for these