FIELD OF THE INVENTION

The present invention is directed to mercury capture systems. The present invention is further directed to methods of making and using mercury capture systems.

BACKGROUND

Mercury is a potent neurotoxin that can affect people of all ages. Artisanal and small-scale gold mining (ASGM) is recognized as the number one source of anthropogenic mercury emissions to air. Miners use mercury to amalgamate gold, concentrating the gold in the mercury and separating it from undesirable gangue minerals. The resulting solid amalgam is between 40-60% by mass mercury, and is heated by open flame to evaporate the mercury, revealing the processed amalgam (sponge gold or doré). The processed amalgam is estimated to be ˜5% by mass mercury. The processed amalgam is then brought to a gold shop where it is further heated by the owner/employee of the shop, releasing mercury into the environment. These gold shops are often located in urban/residential areas where others are exposed to high concentrations of the mercury being eliminated. Occasionally, the entire amalgam will be heated in a gold shop.

Currently, miners and gold shop owners routinely heat the amalgam with an open flame torch (e.g., propane, compressed gasoline, etc.). The heating is often done in the open air or using rudimentary retorts. Occasionally, gold shops will employ ventilation systems consisting of blacksmith fans, vacuum cleaners, etc. These systems are ineffective and result in high concentrations of mercury vapor being released into the room and discharged into the surrounding environment.

For example, currently, gold shop owners in South America use untested MCSs of their own design, including (1) ones that do not have a fan to remove the mercury from the shop and rely on the heat from the flame to drive mercury from the room, (2) ones which utilize household vacuum cleaners that return the mercury directly into the gold shop, and (3) ones that pass the heated mercury vapor over a water bath. In the latter system, the system was intended to condense mercury in the water bath, but copious amounts of mercury condense on the outside of the system. In the fall of 2017, gold shops with these MCSs were evaluated while shut-down (i.e., not operating) and the concentrations of mercury were found to exceed 200,000 ng/m3. While operating, concentrations of mercury on the sidewalk outside of the gold shop exceeded 2,000,000 ng/m3, exceeding the detection limit for the spectrometer used to monitor concentrations.

Prior mercury capture systems also include a mercury capture system developed by the US Environmental Protection Agency (EPA) and Argonne National Laboratories in 2008. This mercury capture system was developed for deployment in Brazil and Peru. The EPA design employed components to remove mercury from the burning area. While tested upon deployment, no follow-up work was conducted to determine the efficiency or life span of the EPA MCS.

In 2013, the Minamata Convention, an international treaty signed by over 120 nations, recognized the danger that ASGM pose to both environmental and human health and safety, and sought increased awareness and cooperation to reduce emissions from ASGM with the ultimate goal of replacing mercury entirely. Annex C of the Minamata Convention calls on signatory nations to develop a National Action Plan (NAP) that outlines actions to eliminate the “ . . . open burning of amalgam or processed amalgam” and the “burning of amalgam in residential areas.”

There is a need in the art for improved mercury capture systems that can be employed to (1) separate the user from the toxic mercury vapor evolved, (2) safely transport the mercury out of the location where the amalgam is being heated and away from populated areas, and (3) condense the majority of mercury preventing its emission to the air and allowing the reuse/resale of the mercury.

SUMMARY

The present invention addresses some of the difficulties and problems discussed above by the discovery of new mercury capture systems. The mercury capture systems of the present invention can be used to (1) separate a user (e.g., an amalgam processor, a miner, gold shop owner or employee, etc.) from toxic mercury vapor evolved from an amalgam processing method, (2) safely transport captured mercury out of the location where the amalgam is being heated and away from populated areas, and (3) condense a majority of the captured mercury preventing its emission to the air and allowing the reuse/resale of the recovered mercury.

Accordingly, the present invention is directed to mercury capture systems. In one exemplary embodiment, the mercury capture system of the present invention comprises: at least one conduit extending between a mercury vapor source and a first outlet of said mercury capture system; a fan positioned at the first outlet of said mercury capture system; and a mercury vapor collecting vessel (i) positioned between and (ii) in fluid communication with the mercury vapor source and the first outlet of said mercury capture system, wherein the mercury capture system reduces an amount of mercury within a first outlet fluid passing through the at least one conduit from proximate the mercury vapor source and exiting the first outlet of said mercury capture system. This system desirably reduces mercury to a level of less than about 35,000 ng/m3(or even less) at the source of burning.

The present invention even further relates to methods of making mercury capture systems. In one exemplary embodiment, the method of making a mercury capture system comprises: forming at least one conduit, the at least one conduit being extendable between a mercury vapor source and a first outlet of the mercury capture system; positioning a fan at the first outlet of the mercury capture system; and positioning a mercury vapor collecting vessel (i) between and (ii) in fluid communication with the mercury vapor source and the first outlet of the mercury capture system.

The present invention even further relates to methods of using mercury capture systems. In one exemplary embodiment, the method of using a mercury capture system comprises (I) positioning (a) a mercury capture system near a mercury vapor source, the mercury capture system comprising: (1) at least one conduit extending between the mercury vapor source and a first outlet of the mercury capture system; and (2) a fan positioned at the first outlet of the mercury capture system; and (II) cutting on the fan, wherein the mercury capture system reduces an amount of mercury within a first outlet fluid passing through the at least one conduit from proximate the mercury vapor source and exiting the first outlet of the mercury capture system.

These and other features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims.

