TEN YEARS OF THE NEW ZEALAND USED OIL RECOVERY PROGRAMME
Lindsay Halliday, Greg Slaughter, Michael Rynne, Blaine Totty
Holcim (New Zealand) Ltd, PO Box 6040, Christchurch, New Zealand
New Zealanders produce about 30 million litres of used oil per annum. Its safe disposal
presents a significant environmental issue. Approximately half of the used oil recovered in
New Zealand is co-processed in the cement kilns at Cape Foulwind, near Westport.
Ten years of environmental monitoring data are employed to investigate whether co-
processing used oil in cement kilns is consistent with environmental best practice given the
limited options for its disposal in New Zealand. Emission data are used to determine whether
the introduction of used oil for co-processing with coal has any significant effects on the
emissions to air when compared with operation with coal alone.
The emission monitoring results show that the co-processing of used oil has little effect on
the emissions of trace metals and dioxins from the kiln stacks, and that the levels of such
emissions are well within internationally recognised limits.
Keywords: Cement kiln, used oil, product stewardship, heavy metals, emissions.
This paper has three main aims. The first aim is to show the volumes of used oil recovered by the
Used Oil Recovery Programme (UORP) since its inception in 1996. The second aim is to outline
the co-processing characteristics of cement kilns and to put these in the context of alternative outlets
for used oil in New Zealand. The third aim is to present some detailed data on the kiln stack
emissions that have been gathered since 1996, and to compare the emissions performance when
used oil was being co-processed with coal with the emissions performance when only coal was
being used as fuel.
Holcim (New Zealand) Ltd is involved with the manufacturing of cement, lime, aggregates and
ready mix concrete throughout New Zealand. Geocycle is a wholly owned subsidiary of Holcim
(New Zealand) Ltd and is charged with managing the company’s supply and use of alternative fuels
and materials for cement production. Over the last 10 years, the predominant alternative fuel
supplied by Geocycle for the use in cement production has been used oil.
3. The Used Oil Recovery Programme (UORP)
In 1996 the UORP was established to collect used oil and supply it to Holcim’s cement plant in
Westport and to the rerefining plant operated by Dominion Oil Refining Company in Auckland. Co-
processing of used oil began at the Westport Works on a continuous basis during 1996, and with the
closure of the rerefining plant during 1999, Holcim became the sole outlet for used oil from the
UORP. The programme was originally established in response to a growing industry concern that
used oil was not being recovered and used responsibly (MfE 2001).
Funded largely by Holcim, Shell, BP, Caltex, and D R Britton Ltd (Valvoline), and in partnership
with the Ministry for the Environment, the Used Oil Recovery Programme is designed to give oil
producers, users and regulators the assurance that their used oil is being collected, transported and
used or disposed of in an environmentally responsible way. Geocycle collects used oil from
hundreds of enterprises which range from oil producers, major industrial oil consumers, to small
garages and workshops. As part of Geocycle’s business systems it aims to meet rigorous quality
standards and high levels of environmental compliance. At the cement plant, the used oil is co-
processed with coal as a fuel for the production of cement.
Within the UORP, the used oil is collected on a nationwide basis by three transporter/collection
businesses, two in the North Island, and one in the South. The transporter/collectors operate under a
written Protocol for the Collection and Transport of Used Oil. Under the Protocol, the used oil must
be tested to show that its flashpoint is above 60ºC and be largely free of contamination, prior to its
delivery to Holcim’s ships.
During the calendar years 2005-2006, an annual volume of approximately 15 million litres of used
oil/ships slops was supplied to the Westport Cement Plant as backloads aboard Holcim’s two
cement ships. Westport is in a fairly remote location on the West Coast of the South Island and the
availability of backloading has been key to the ongoing success of the logistics aspects of the
UORP. Of the 14.7 million litres delivered to Westport during 2006, approximately 13 million litres
was used oil from within New Zealand. This volume of used oil represents approximately 43% the
30 million litres of used oil estimated to be available for collection in New Zealand (MfE 2001),
and probably more than half of the used oil actually recovered in New Zealand. It is difficult to
obtain accurate figures for the total amount of used oil being recovered in New Zealand, but during
2001 it was estimated that 9 million litres was unaccounted for and could have been disposed of in
an environmentally unsafe manner (MfE 2001).
Used Oil and Slops Deliveries to Westport Works
Third Party tonnes
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 est
The New Zealand Used Oil Recovery Programme competes for the supply of used oil with other
consumers and this also appears to be the case in other developed countries. For example, in the
European Union during 1999 it was estimated that 28% of total volume of used oil was disposed of
illegally (Monier and Labouze, 2001).
4. Alternative Outlets for Used Oil in New Zealand
A survey of regional councils in New Zealand undertaken by Geocycle in 2005 (unpublished
internal report) indicated that at least 21 air permits, in addition to Westport Cement Plant, authorise
the burning of used oil throughout NZ. Consented activities included industrial boilers, burnt lime
manufacturing and hot mix asphalt production. It was noted as part of this survey that oil and
emissions monitoring requirements attached to these air permits were extremely variable between
regions. In many cases there was no requirement for monitoring of the quality or quantity of the
used oil or their air emissions.
Likely alternatives for used oil include heating for horticultural purposes and during colder months,
used oil is consumed as fuel for space heating in workshops etc… The information available on the
effects of combustion of used oil via the above-mentioned outlets in New Zealand appears to be
based on overseas data with a lack of reports on actual performance locally (Woodward Clyde
2000). Additionally, there is a general lack of information on the quantities of used oil consumed
via these outlets. A quantity of used oil continues to be used as a dust suppressant on unsealed
roads, particularly in the Otago and Southland Regions where it remains a permitted activity
(Environment Southland 2003).
5. Holcim Westport Cement Plant
West Coast Regional Council air permit 94073 allows for the co-processing of up to 50% used oil
with coal as fuel at Holcim’s Cement Plant. Conditions of the air discharge permit require Geocycle
and Holcim to meet quality criteria for the used oil, employ continuous monitoring of flue gases and
undertake regular stack monitoring from the three cement kilns. The used oil delivered to Westport
is required to be tested for metals, chlorides, sulphur, and PCBs before being used.
Dust emissions are controlled from the plant with the operation of electrostatic precipitators.
On an annual basis, used oil replaces about 17,000 tonnes of the coal traditionally used to fire the
three high temperature cement kilns. There are two identical small kilns (98m long with a burning
zone diameter of 3.3m) and a third, larger, kiln with a diameter of 3.45m and length of 110m. The
Westport Works produces approximately 500,000 tonnes of cement a year.
The used oil firing system at Westport comprises a road tanker unloading facility, a tank farm
including 6 storage tanks each of approximately 200 cubic metres capacity, and associated
pumping, heating and flow measuring systems so that the used oil can be independently co-
processed in each of the three kilns as required. The kilns are fed with raw material in the form of
slurry, and are heated by means of pulverized coal firing systems (Figure 1). The used oil is co-
processed via the main burner, supplementing the coal.
Unlike most other heating applications that employ used oil, the extreme heat required for cement
production almost entirely destroys organic contaminants. This is due to the extreme temperatures
under which cement is manufactured (material temperature approximately 1480ºC, with gas
temperatures up to 2000ºC) under oxidizing conditions and with long gas residence times. As is the
case for coal, most ash solids from used oil are incorporated into the cement product. The World
Business Council for Sustainable Development (WBCSD) (WBCSD, 2006) estimates that the
typical residence time of combustion gases in a typical cement kiln is more than five seconds at a
temperature higher than 1,000°C. By contrast, gas residence time in a typical incinerator is only two
seconds. Residence times for combustion gases at temperatures higher than 1,000°C ex the main
burners in the kilns at Westport have been calculated to be about 3.5-4 seconds for kilns 1 and 2,
and longer for kiln 3. This is less than the residence time quoted by the WBCSD, but is still about
twice the residence time at high temperature quoted for incinerators (Holcim (New Zealand) Ltd
2004). The United Nations Environment Programme (UNEP) (UNEP, 2007) recommends used oil
is best used as a fuel in cement kilns.
Figure 1. Schematic of a Westport Works cement kiln
6. Emission Monitoring and the Effects of Co-processing Used Oil
In addition to the monitoring of the stack gases required for compliance with resource consent
requirements, Holcim requires that detailed testing of the stack gases is performed on an annual
basis by suitably qualified and independent external consultants using standard methods. Six rounds
of such testing have now been performed at the Westport Works over the period of 1999 to 2006.
The testing includes measurements of trace metals and of dioxins.
The detailed test results below are reviewed to determine whether the co-processing of used oil has
any significant effects on the emissions. Emission test results for the kiln(s) operating with coal
alone were compared with emission test results for the kiln(s) operating with oil being co-processed
with coal. Previous work undertaken by Holcim suggests that the adverse effects of the current
stack emissions on the local environment are not significant (Holcim (New Zealand) Ltd 2004).
The kilns are fed with raw materials (slurry) from a common supply and are fired with coal and
used oil. While there are some operational differences between the kilns, it is considered that any
major differences in emissions performance due to the co-processing of used oil would show in the
emissions test results, because the operating temperatures and stack gas cleaning systems are
similar for all kilns.
6.1 Trace Elements in Raw Materials and Fuels
As with all processes, the raw materials used within the cement making process contain varying
levels of trace metals. Table 1 shows trace elements commonly found in the earth’s crust, in
limestone, coal and used oil.
Table 1: Concentration of elements in the Earth's crust and in raw materials used at Westport
Slurry HNZ Coal HNZ Used Oil HNZ Clinker HNZ Kiln Dust HNZ
Element 2003 (Range) 2003 (Range) 2002 (Range) 2003 (Range) 2003 (Range)
(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)
Antimony 1 <0.4 <0.4 <0.4 <0.4 <0.4
Arsenic 5 5-7 4-7 <1 11-13 22-13
Barium 250 NDA <1 NDA NDA NDA
Beryllium 6 NDA NDA NDA NDA NDA
Cadmium 0.15 0.2-0.3 <0.1 0.17-0.32 <0.1 4.5-15.7
Chromium 200 25-50 1-10 <1-2 36-47 28-39
Lead 16 2.7-3.5 1.9-3.1 26-106 0.5-1.9 89-304
Mercury 0.5 <0.1 <0.1 <0.05 <0.1 <0.1
Nickel 80 14-32 2-3 <1 14-22 11-16
Selenium 0.09 NDA NDA NDA NDA NDA
Thallium 0.6 1.3-3.7 0.1-0.8 <0.1 <0.2 31-226
Vanadium 150 <100 <100 <50 <100 <100
Zinc 132 13-19 5-12 352-739 43-55 41-395
Bromine 1.6 10-17 NDA NDA NDA NDA
Chlorine 314 5-8 11-27 736-1500 NDA NDA
Fluorine 300 NDA <1 <1 NDA NDA
Notes: 1. Data reported is a range of results of individual analyses; 2. NDA – no data available
6.2. Trace Metal Emissions
The gas condition for all measurements in this paper is dry, 0oC, 1 atm, 10% oxygen. Figure 2
shows a comparison of the average emissions of trace metals while Figure 3 compares the results
with the EU limits for cement kilns. Further details of the measurements performed at Westport are
provided in a paper presented at the recent IUAPPA World Congress (Halliday et al, 2007).
A comparison of the average trace metal emissions (Figure 2) shows that the trace metal emissions
for the co-processing of used oil largely lie within the envelope set by the emissions for coal alone.
The trace metal emissions are all well within the EU limits (Figure 3).
Zn 45 As Trace Metals Emissions
40 (Average 1996-2006)
V 30 Cd
Tl 5 Co
Mn Pb Coal Only
3 Coal and Used Oil
All units: µg/Sm
Figure 2. Comparative historic average emissions of trace metals at Westport Works.
Westport Trace Metals Emissions - Coal and Used Oil
(comparison to EU Limits)
Cd +Tl (Coal Only)
Cd +Tl (Coal and Used Oil)
Limit for Cd +Tl
Sb + As+Pb+Cr+Co+Cu+Mn+Ni+V (Coal Only)
Sb + As+Pb+Cr+Co+Cu+Mn+Ni+V (Coal and
0.2 Limit for Sb + As etc
Hg (Coal Only)
1996 Dec-01 Jan-03 Dec-03 Dec-04 Nov-05 Sep-06
Figure 3. Comparison of trace metal stack emissions with EU limits.
6.3. Dioxin and Furan Emissions
Figure 4 shows the dioxin/furan emissions results for the kilns.
Westport Works Dioxin and Furan Emissions to Stacks
ng/Sm3 at 10% O2, STP
Coal and Used Oil
1996 Dec-01 Jan-03 Dec-03 Dec-04 Nov-05 Sep-06
Figure 4. Dioxin and furan emissions to the stacks.
Note that the units for dioxin/furan measurement are all I-TEQ/Sm3 at 10% O2, and that the
reported results include congeners not detected at half of their limits of detection. Considering
emissions of dioxin (Figure 4), the results plotted for operation with/without used oil show similar
trends. The EU, and commonly recognised limit for dioxin emissions on an international basis is 0.1
ng/Sm3. Thus the dioxin emissions for the kilns are all well within the recognised limit.
Measurements of dioxin emissions from 16 cement kilns in Germany over a period of 10 years
showed an average stack concentration of about 0.02 ng/Sm3 (UNEP, 2003), indicating that the
performance of the Westport kilns compares well with current practice. There is no result for coal
alone for December, 2004, as all three kilns were co-processing used oil.
6.4. Effect of Used Oil on Carbon Dioxide Emissions
Figure 5 shows the quantities of thermal energy provided by coal and used oil at Westport Works
and the downward trend in the amount of CO2 (kg) produced per tonne of cement.
Westport Works CO2 Emissions (kgCO2/t
CO2 per tonne Product
TJ per annum
Specific CO2/t Cem
Total Energy (TJ/yr)
Coal Energy (TJ/yr)
800 Used Oil Energy (TJ/yr)
1990 1992 1994 1996 1998 2000 2002 2004 2006
Figure 5. Westport Works CO2 Emissions
The combustion of used oil produces approximately 74 kg CO2 per GJ of (net) thermal energy
gained, while for coal the figure is 89 kg CO2 per GJ. Thus there is a reduction in CO2 production of
about 17% for used oil compared with coal per unit of useful thermal energy gained.
The downward trend in the amount of CO2 (kg) produced per tonne of cement (Figure 5) is assisted
by two main factors: an improvement in the thermal energy efficiency of the Westport plant and the
gradual increase in the quantity of used oil co-processed. During 2006, used oil provided 18.0% of
total process heat for the kilns, and reduced CO2 production by 3.1% compared to coal-firing only.
Boughton and Horvath (2004) recently carried out an environmental assessment of used oil
management methods. They investigated the three primary ways that used oil is managed in the
United States: re-refining into base oil for reuse, distillation into marine diesel oil fuel, and
marketing as untreated fuel oil. They concluded that heavy metals-related toxicity dominated the
comparison of management methods. Zinc and lead emissions from combustion were the primary
contributors to the terrestrial and human toxicity impact potentials that were calculated to be 150
and 5 times higher, respectively, for used oil combusted as fuel than for re-refining or distillation. It
was stated that the re-refining and distillation methods and associated product markets should be
strongly supported because they were environmentally preferable to the combustion of unprocessed
used oil as fuel.
The test results for Westport show, that while used oil has much higher concentrations of zinc and
lead than the coal it replaces, its co-processing in the kilns appears to have no significant effect on
the stack emissions of those metals. Boughton and Horvarth (2004) concluded that re-refining and
distillation was superior to combustion of used oil as fuel, largely on the basis of relative heavy
metals emissions. However, their study did not evaluate high temperature cement kiln recovery
where such metals are substantially captured within the process (UNEP, 2007). Irrespective, given
the lack of a re-refining facility in New Zealand, and in the absence of a comparative study of re-
refining and cement kiln energy recovery, the combustion of used oil in the kilns at Westport
presents a useful alternative and perhaps a best practice option for New Zealand.
Table 1 shows how the different metals are captured within the clinker and kiln dust. Apparently,
any additional zinc or lead above the quantities that would be provided by coal alone preferentially
migrates to the clinker and dust to the extent that stack emissions are not significantly affected.
The results presented here show that co-processing of used oil can be carried out in the kilns at
Westport Works with little effect on the stack emissions. The remainder of NZ’s used oil is burned
in combustion processes with lower temperatures and residence times and often without any
environmental controls. It is likely that co-processing of used oil at the Westport Works is currently
the best available technology for the disposal of used oil in New Zealand. However there is a lack
of information on the emissions performance of the other methods of used oil combustion in New
Zealand, and further work is necessary to confirm this proposition.
• The emission monitoring results spanning ten years show that the co-processing of used oil has
little effect on the emissions of trace metals and dioxins from the kiln stacks, and that the levels
of such emissions are well within limits that are recognised on an international basis.
• Co-processing of used oil has significantly helped reduce the emissions of CO2 at Westport
Works when compared with operation if only coal had been used for process heat.
• Volumes of used oil recovered via the UORP have recently (2006) been about 11 million litres
with about a further two million litres coming from other sources within New Zealand (eg from
other used oil recovery programmes including some sponsored by territorial authorities). Other
sources, mainly ships slops, provided a further two million litres input for the kilns, for a total of
approximately 15 million litres.
• The continued operation of the New Zealand UORP provides oil supplies, users and regulators
the assurance that used oil is being collected, transported and disposed of in a responsible
manner in line with environmental best practice.
Boughton R, and Horvath A, (2004) Environmental Assessment of Used oil Management Methods.
Environmental Science and Technology, 38:352-8.
Environment Southland (2003) Southland Regional Land Transport Strategy. Annual Report
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Oil Recovery Programme. CASANZ Conference, Brisbane Sept 2007.
Holcim (New Zealand) Limited (2004) Continuation of Alternative Fuels and Raw Materials
Program. Assessment of Environmental Effects submitted to the West Coast Regional Council.
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Ministry for the Environment (2001) Options for Used Oil Recovery in New Zealand. 31 August
2001. MfE report number ME629. (www.mfe.govt.nz/publications/waste/used-oil-recovery-aug01/)
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the Regeneration and Incineration of Waste Oils. European Commission. DG Environment, A2
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Quantification of Dioxin and Furan Releases, 1 st Edition, May 2003
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USEPA (1995) United States Environmental Protection Agency, Compilation of Emission Factors
AP42, Fifth Edition, 1995
WBCSD (2005) World Business Council for Sustainable Development. Guidelines for the Selection
and Use of Fuels and Raw Materials in the Cement Manufacturing Process - Cement Sustainability
Initiative (CSI) December 2005
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Effects Associated with the use of Waste Oil as a Dust Suppressant. Prepared for the Ministry for
the Environment, August 2000. AA35080036