Battery recycling
The batteries are made up of a set of devices that transform chemical energy into electrical energy. These systems contain heavy elements in their structure, which are toxic substances for the environment and the human being.
These devices by placing them in landfills pollute the soil, groundwater, compromising the quality of the environment and the health of the population and wildlife. Each battery that is disposed of improperly contaminates an average square meter and takes more than a thousand years to degrade.
Environmental impact
The batteries have a high pollution capacity, although they only represent 0.2% of the garbage. A single alkaline battery can contaminate up to 175,000 liters of water, while a micro button cell can contaminate up to 600,000 liters of water. The biodegradation time of these is more than 1000 years.
The presence of batteries in household waste causes a polluting effect, because, in addition to corrosion, they undergo a process of fermentation of organic matter, which, when reaching high temperatures, acts as a reactor accelerating and concentrating the degradation process. Finally, another problem is the air pollution occasioned by the burning of the batteries, that generates dangerous pollutants such as mercury vapor in some cases, because not all batteries contain mercury in their composition.
Battery classification
Batteries can be classified both by the state of the electrolyte, its shape its reversibility when generating energy and its internal components. Depending to the state of the electrolyte they are classified as wet and dry, according to the state of aggregation, the dry ones are characterized in that the electrolyte is in the form of a gel, while in the wet ones the electrolyte is in liquid form and is generally an acid.
By reversibility, the batteries can be classified into primary and secondary, in the primary, the chemical reaction is carried out in only one direction and end when all chemical energy is consumed, while in the secondary the chemical reaction is reversible and can be recharged by an external source of energy. According to the internal components, most of these have a cathode that is an oxidizing agent and an anode consisting of a metal that undergoes corrosion in various degrees of the electrolyte.
Recycling according to the type of battery
To be able to recycle batteries or accumulators, these must be separated because the different components present in these devices can contaminate the metals that are to be recovered. The existing information on the recycling of these devices is scarce and not very specific, so it is an issue that should be investigated in a way that allows reducing the environmental impact, as well as generating guidelines that allow proper management of these. Among the types of recycling known are those shown below.
Recycling by
Hydrometallurgy
This method consists in performing an acidic or basic leaching of the contents of the batteries to separate the metals present in them in a solution. It is commonly used for metal recovery like iron, manganese, and zinc. Among the advantages of this method are that it is simple, does not generate gaseous emissions, requires low implementation costs, and allows the total separation of metals.
The disadvantage is that it generates wastewater contaminated with heavy metals and acids.
Recycling by
Pyrometallurgy
This process involves the recovery of materials using high temperatures, that is, it is a method that involves the transformation and separation of components from a thermal treatment of the residue in a reducing medium and the separation of volatile metals. The advantage is that the simple process that allows the recovery of valuable metals generating a minimum amount of liquid waste. The disadvantage of this technology is that it is not versatile and consumes a lot of energy for the evaporation of metals.
Recycling by
Chemical stabilization
It is a process that happens in three phases the first is the reaction phase which begins with the pre-selection and crushing of the batteries in a reactor, where the crushed mass is mixed with stabilizing chemical agents, sodium sulfide, sodium hydroxide, and sodium carbonate, inducing the precipitation of certain metals. Neutralizing the harmful effects of these devices.
The second phase is the recovery phase, this is done by absorbing the ammoniacal vapors produced on sulfuric acid, obtaining ammonium sulfate, which can be used as fertilizer. Finally, there is the classification phase, where the inert mass is separated from the scrap metal, which forms the battery housing and destined for a subsequent recycling operation. This process applies to standard or alkaline batteries.
Lead Battery Recycling
In this process the batteries are cut to be able to extract the internal component, in this case, lead, and drain the electrolyte which must be taken to a wastewater treatment system, this treatment system must be composed of a sedimentation pit with traps that allow to trap suspended solids and sediments caused by the release of material from the plates inside the accumulators. Finally, the electrolyte is sent to a reactor to neutralize it, with a chemical agent that fulfills this function. The removed metal is carried out to a reduction process to obtain metallic lead, which can be used for national and international marketing.
When the technology for the recycling of components is not available or involves high costs, physicochemical processes are used to reduce the mobility of heavy metals. Among these techniques can mention the confinement in hermetic containers, encapsulation with cement, vitrification at high temperatures, stabilization by aggregate of chemical agents that form insoluble compounds with metals, among others. Once the residue has been treated with some of these forms, it can be disposed of in the landfill. When using cement encapsulation, it is advisable to place the batteries in airtight containers with a basic reagent to neutralize the products, avoiding acidic alterations that could damage the container.
Places to recycle batteries in Costa Rica
According to the legislation in force in Costa Rica, hazardous wastes such as batteries or accumulators must be treated by the entity that supplies said device, that is, once these devices end their useful life, they must be taken to the companies or places where they were acquired in order for them to correctly dispose of them. Currently, in Costa Rica, batteries are usually deposited in household or industrial waste, causing environmental pollution. However, in the last years in the country, different recycling sites have been created, which seek to give a better management of the waste that is generated day by day in the country, among these can be mentioned are: