Large and small artisanal gold miners are using Rocker Boxes (also known as cradles) to recover gold in a sustainable and effective manner. Like the sluice box, a rocker box is an old-fashioned, manual device that uses riffles and a carpet to trap gold.
Unlike sluices, which have their own water supply, the rocker box depends on the water that is poured through it. Because it uses a lot of water, the agitation of the rocking box helps to carry the lighter fraction of sand over the riffle bar and trap the heavy sand and gravel.
Water Conservation
Gold mining involves the extraction of valuable metals from a placer deposit (a loose alluvial stream) by digging, shoveling, or suctioning with large dredges. While the dredging method is less labor intensive than panning, it is still an environmental concern, since the process requires a lot of water and disturbs the natural environment. Consequently, miners are required to follow strict guidelines in limiting the amount of water used. One such guideline is to only extract the maximum amount of sediment necessary for the desired result. The rest of the material should be left in its original location to avoid environmental damage.
A rocker box is a small device that resembles a sluice box and can be used to find gold in a river or creek. The rocker box has riffles and a screen to catch fine gold. The riffles are designed to create dead zones in the current to allow the heavy, gold-bearing materials to settle. The less-dense materials are carried away with the current as tailings, while the gold-bearing concentrates fall behind the riffles and can be collected as a concentrate or amalgamated with mercury.
Compared to other forms of small-scale mining, the use of rocker boxes allows for greater concentrations of gold to be recovered in a shorter period. It also uses less water, making it a suitable option for regions with limited supplies of water. In addition, it does not require large amounts of machinery or expensive materials to build. This makes the rocker box a more cost-effective alternative to other forms of small-scale mining, such as mercury amalgamation.
Small artisanal gold mining has been the main economic activity in northeast Antioquia for years. However, the industry is a root cause of several environmental problems such as shortage of water (8.8%), dehydration of the brook (10.6%), soil erosion (20.8%), and destruction of the ecosystem (7.0%).
Moreover, the COVID-19 pandemic led to more humanitarian initiatives and offers by the artisanal and small-scale mining sectors. For example, more gold miners started human development projects, from financial contributions to mine-funded hospitals, and emphasized the need for sustainability in their operations.
Environmental Impacts
During the gold rush, a rocker box was an essential piece of equipment for the placer miner. However, the use of this type of mining equipment has waned since then. Newer gear is more efficient in terms of gold collection. However, the rocker box can still be used in certain areas with favorable results.
Basically, the rocker box is a high-sided, open-end box that has riffles in it to trap gold in the same manner as a sluice. The advantage of a rocker box is that it requires less water than a sluice, which can be helpful in areas with limited water availability. It also works with a rocking motion, allowing the riffles to trap more gold than simply agitating the gravel with water.
The rocker box consists of a hopper that is open on one end and a sheet-iron bottom with holes punched into it. A canvas apron is placed under the screen and several wooden riffles are positioned in the box. When the paydirt is shoveled into the hopper, the miners pour water over it and then rock the box back and forth. This allows the heavier rock, gravel, and cobbles to stay in the hopper while the lighter materials are carried down through the riffles.
After the riffles, the material would fall into a trough at the tail. This trough was then covered with cloth such as miner’s moss that would trap the fine gold. Once the fine gold had been collected, the riffles were removed and the black sand with any gold flakes was hand-picked from the box and panned for its precious metal content.
The process is labor intensive but can produce more gold in a day than can be obtained with a gold pan. The disadvantage is that it takes two men to operate the device properly (one to shovel, carry, and wash the paydirt, and the other to rock and clean the box). In addition, a good rocker box requires more space than does panning, making it an inefficient choice for smaller placer sites.
Social Impacts
A rocker box is a gold mining tool that is a precursor to the modern sluice. It is small, portable, and allows miners to operate in areas where there is not enough water to run a sluice. A rocker box has riffles and carpets in it to trap gold and is operated by pouring water on top and then rocking the tool like a cradle.
Gold prospectors used rocker boxes during the California Gold Rush to separate gold from gravel and sand. They were also fairly portable which was an advantage as they often moved to new diggings.
While modern placer miners employ sophisticated equipment such as excavators, bulldozers, and dredges to mine for gold, the artisanal miner continues to use these rudimentary tools. These miners typically work in developing nations, where they are seeking to escape poverty and unemployment. They are known as galamsey miners in Ghana, orpailleurs in France and Brazil and garimpeiros in Colombia, Venezuela, Suriname, and French Guiana.
Galamsey miners use a variety of mining methods, from panning to using sluice boxes and rocker boxes to extract gold. They use these rudimentary tools because they do not require advanced technology, and they can be cheaply and easily assembled and used. They do not have the benefits of safety or insurance that larger miners enjoy, and they are at risk for exposure to mercury, which is toxic to humans.
A traditional rocker box had a wooden frame with two solid wood handles which the miner grasped to rock it from side to side in a sitting or standing position. The bottom of the box was a trough that held a carpeted mat and a series of riffles that trapped gold and black sand. It was important to not overly vigorously rock the rocker box, as this would increase the loss of fine gold particles out through the tail.
During the gold rush, placer mining was highly destructive to the environment. Excessive use of mercury, a toxic substance, led to environmental damage including the pollution of rivers and streams and the deforestation of landscapes. Hydraulic mining, which relied on high-pressure water jets to blast away the sides of hillsides, was even more devastating as it led to erosion and siltation of rivers and streams.
Technology
Gold mining is notorious for causing environmental damage. In fact, it is one of the few extractive industries whose harms exceed its benefits. But while transitioning away from fossil fuels required decades of research into clean energy technologies, a move away from extractive gold could be accomplished more quickly.
In addition to pollution from the use of mercury and other toxins, modern industrial mines produce a huge amount of wastewater that contaminates local waters. In many cases, this wastewater contains heavy metals such as cyanide, arsenic, and mercury. The water can also contain contaminants from the dumping of mining residues such as barren rock, sand, and other debris. These toxic pollutants can have a wide variety of harmful impacts on ecosystems and human health, including toxic fungi and other fungal diseases that affect human health.
Despite these problems, there is no reason to continue a largely destructive approach to gold mining. The world has ample reserves of recycled gold, which has a much smaller impact on ecosystems and communities than does primary gold (Fritz et al 2020). Gram for gram, recycled gold is just as valuable as raw gold produced by industrial mining, but it can be produced in self-contained, industrial facilities that are far less likely to release hazardous toxins and emissions or disturb landscapes than those used in large-scale industrial mining operations.
Artisanal and small-scale gold mining in northeast Antioquia, for example, has benefited some Sustainable Development Goals—such as poverty reduction and hunger elimination—at the expense of others, such as human health and sustainable water management (Sustainability Solutions 2022). Shifting away from an extraction paradigm to a circular gold economy would address all of these issues and advance sustainability goals at a lower cost to human welfare.
To accomplish this, we need a broad coalition of stakeholders working together. To start, major intergovernmental lenders and endowment managers should make clear that they will not finance new mining projects, as they have done with coal-powered power plants. They should require mining companies to commit to accelerating the retirement of existing mines and promote a shift to using recycled gold. Consumers can choose to buy recycled gold or not purchase it at all, thus reducing demand for primary gold and putting pressure on mining companies to reduce their exposure to climate risk.