13. Health, Safety and Emissions to the Environment from Alumina Refineries

The health and safety of personnel working in industrial facilities must be secured by reasonable protection measures. Likewise, the protection of the environment from the operation of the industrial facilities must meet the emission standards set by the authorities to obtain and maintain the License to Operate these industrial facilities. The prime focus of this chapter considers the Health, Safety and Environmental (HSE) issues from a process point of view. This means that protecting personnel health is limited to a description of the major chemicals that the personnel can be exposed to. Thus, leaving it up to the refinery management to ensure that adequate procedures and protection measures to protect the health and well-being of their personnel during their working hours is enforced. Several cases of hazardous events in alumina refineries, including the bauxite residue storage area, introduces some of the process safety issues that have occurred in the past. From there, an introduction to Functional Safety is made representing a systematic approach to deal with this subject in today’s alumina refinery design and capacity expansions. Safety aspects of operating high pressure and temperature equipment in the digestion area are touched upon as well. Sources of the major gas borne emissions to the Environment from the alumina refinery operation within allowable local emission limits is discussed for NO_x, CO, SO_x, VOC, CO₂, and particulate matter. Time has shown that authorities in general tend to tighten the allowable gas borne emissions to the environment and in many places rightfully so. Anticipating that this trend will continue in the future, it is important to understand current days technology with a view to future possibilities for acceptable solutions. In the near-term Natural Gas will be replacing HFO to lower SO_x emissions and the “Carbon Footprint” of Alumina Refineries. In the medium-term, the ESP may be gradually outplaced with Fabric Filters (FF) or ESP/FF hybrids using “Tailor made” catalyst to reduce emissions of NO_x and VOC’s and eliminate emissions of dust plumes when a power failure happens. In the long-term we may expect to see a gradual replacements of fossil fuels with “Green Hydrogen” to reduce the “Carbon Footprint” of future Alumina Refineries to almost ZERO.