Used Oil Utilization for Lime Production as Hazardous Waste Minimization

In line with the rapid advance of technology and current development, a variety of industrial activities came to existence [1]. The impact of this rapid industrial development, is inversely proportional with environmental condition [2]. Pollution increases caused by hazardous materials which are the residuals of production processes [3]. The more industrial development, the more accumulation of hazardous waste (B3-waste) produced [2]. B3-waste pollution potential is quite significant so a proper management is needed. One of B3-waste that needs to be well managed is used oil [3,4]. Used oil contains some heavy metals, on of which is Pb (lead). Lead heavy metal contamination has become an environmental problem [4].


Introduction
In line with the rapid advance of technology and current development, a variety of industrial activities came to existence [1]. The impact of this rapid industrial development, is inversely proportional with environmental condition [2]. Pollution increases caused by hazardous materials which are the residuals of production processes [3]. The more industrial development, the more accumulation of hazardous waste (B3-waste) produced [2]. B3-waste pollution potential is quite significant so a proper management is needed. One of B3-waste that needs to be well managed is used oil [3,4]. Used oil contains some heavy metals, on of which is Pb (lead). Lead heavy metal contamination has become an environmental problem [4].
At PTFI, used oil becomes the main concern. In the last three years, used oil accumulation increased in line with the increase of production capacity, with the opening of new mine projects. As of December 2015, the used oil generated was 1,119,797 gallons, experiencing a surge compared to previous years. Lime plant consists of a rotary kiln with nominal design 400 tons of lime per day and which can range produce 200-380 tons of lime per day. The exhausts gases from the kiln are fed through a dust collector bag house and then released to ambient air through a single steel stack [5]. Lime plant has obtained new permit from the Minister of Environmental and Forestry Number 07.03.06 year 2015 on Hazardous Waste Management Permit [6]. The testing was performed using methodology and procedures in accordance with Approved Apex Instrument Method 5 by USEPA (United States Environmental Protection Agency) concerning particulate sampling and Method 29 USEPA concerning metals as well as gaseous emission including CO, SO 2 , NO 2 , HCl and HF. All test works were completed according to Government of Indonesia Environmental Impact Management Agency (BAPEDAL) methods, which are equivalent to USEPA methods [6].

Methods
This research applied a descriptive method which describes the processes of used oil utilization at lime production plant. The process of reclaiming the used oil went through several processes and involved several parties (department). This research will portray processes from the beginning, i.e. when the used oil was produced, to the oxidation process resulting in emission.
The description stages of used oil reclaiming process are as follows ( Figure 1): 1. Used oil management, involving used oil generation and transportation.
2. Lime plant operational requirements, covering used oil characteristics, utilization process, and emission tests. In 2015 used oil generation reached 1,119,797 gallon. Used oil produced by operations and maintenance departments will be transfered and compiled at a specific reception area for B3-waste. i.e. Mill Transfer Point. The used oil in the transfer point, before the pumping to be done, will be drained first so that the water content in the used oil can be reduced. In the transfer point, used oil is then pumped into a container called the tank-tainer with a capacity of 5,000 gallons. The used oil that has been in the tank-tainer is then transported to the used oil tanks with capacity 200.000 gallons.

Lime plant operations
Limestone processing plant was established with its maximum production capacity 400 metric tons of quick lime (CaCO 3 ) per day. The limestone production is adjusted with the ore-processing plant's operational needs and the other usage such as covering stone mixer in the mining area. Lime dehydrator is utilized to convert the limestone into hidroxide form and reserved for limestone need fulfilment in concentrators so limestone purchases from outside PTFI area can be reduced. In the burning process ( Figure 3), the used oil and the diesel fuel are mixed and heated on a preheater at 46°-70°C and then injected to the burning oven at 850°-960°C.

Control equipment and stack
Main bag house (powder dust system) consists of four fragmentary compartments. Each compartment contains 336 filter bags. Filter bag uses Huyglass-materials, which is resistant to temperature up to 260 o C. Air from rotary kiln are sucked into bag house using ID fan through the filters and leftover the dust particle at filter bag's surface.
The stack dimension is 29.6-meter high and 2.5-meter in diameter. Four sampling ports at right angels' position were installed with a 10 cm diameter each and at a level of 20.4 meters from the base and 1.2 meters above platform. The stack is equipped with steel ladder and safety climbing device. The gas temperature is approximately 130 o C. The stack tested at lime plant had an estimated temperature and dimensions as shown in the Table 1 below. For aiding in the representative measurement of pollutant emissions and/or total volumetric flow rate from a stationary source, a measurement site where the effluent stream is flowing in known direction selected. Then, the cross-section of the stack divided is into a number of equal areas. After that, a traverse point is located within each of these equal areas (Table 2). This method is commonly applicable to flowing gas streams in stacks.

Emissions monitoring
As an effort to manage the exhaust air quality from the limestone-     processing plant so that it complies the required quality standard, a number of maintenance action on 200 thousand liters of taks and monitoring action on exhaust air from oil-water separator have been taken. This step is the follow up action on the used oil utilization permit extension until oil/used oil composition ratio is 80%.
As an effort to manage the exhaust air quality from the limestoneprocessing plant's chimney so that it complies the required quality standard, the following seven steps must be taken: 1. Conducting routine maintenance on the pollution control devices such as filter bag on the baghouse dust collector, ID fan maintenance, oil heater according to the maintenance schedule.
2. Controlling the air pressure and the fuel debit that influence directly on the exhaust air quality from the chimney.
3. Controlling the debits of fuel, use oil, burning oven temperature and other parameters that directly influence the exhaust air quality from the chimney. Monitoring the air quality at the limestone plant is conducted twice a year. This monitoring is done periodically so that the exhaust gas complies the ambient air quality standard and refers to the Decree of the Minister of Ennvironmental and Forestry Number: 07.37.06 year 2015, effectively updated on 3 June 2015. The measurement of exhaust gas emission has to be conducted internally and externally. Table 3 demonstrates the result of exhaust gas emission monitoring in 2015.

Conducting monitoring internally on the exhaust emission from
The measurement of used oil characteristics is done twice a year (Table 4) to identify the heavy metal that is contained in the oil as well as other contents such as PCBs, water content, etc. Fifth dictum: PTFI is obliged to provide B3-waste temporary storage facility. This facility must have a building plan with storage capacity suitable with the type, number and characteristics of B3-waste to be stored. It also has one tank unit with 200 tons capacity with water resistant basin to prevent any spills. Now has a temporary storage facility at a transfer point and has already built a 200-tons capacity tank ( Figure 4).

Sixth dictum:
In the sixth dictum, it is required that the used oil must comply with the standards (Table 4). Based on the stated regulatory requirements above, the measurement results that have been conducted    can be determined whether the measured parameter exceeds the quality standard.
The above table shows that the used oil characteristics have complied with the required quality standards. For PCBs, the measurement result shows that the value is <20 while in the regulation, there is no clear number or range PCBs contents in the used oil. However, it can concluded that PCBs contents in the used oil not categorized into 'pure' PCBs where their value is ≥ 50 ppm. In the sixth dictum, it is required that the consumption of used oil as a fuel substitution does not exceed 80% from the total fuel needs ( Figure 5).
From the diagram above the biggest ratio of used oil and diesel fuel consumption ratio was recorded in April, i.e. around 65%. However the figure does not exceed or equal to 80%. The smallest ratio was recorded in July, i.e. around 30%. In the sixth dictum, it is also required that the utilization of used oil as a fuel in the lime combustion that uses kiln is equipped with the following tool specifications ( Table 5): The followings are the figures of chimney, rotary kiln facility and baghouse as required. Emission control becomes an absolute requirement in used oil utilization. In the regulations, it is mandatory to conduct emission control twice a year and it cannot exceed the quality standards (Table  3 and Figure 6).

Conclusion
The utilization of used oil in Lime Plant has met the requirements of the government regulation to minimize hazardous waste in order environmental protecting from spillage. Stack emission test to monitor