Apparatus and methods for mercury and precious metal recovery

Abstract

Apparatus and methods for mercury and precious metal recovery are provided. The apparatus includes a granulometric separator for separating a feed by particle size; a centrifugal concentrator in flow communication with the granulometric separator for isolating and concentrating an elemental mercury-containing fraction of the feed; and an accumulator tank for collecting elemental mercury from the elemental mercury-containing fraction. The accumulator tank has an inlet in flow communication with the centrifugal concentrator; an outlet; a plurality of baffles defining a serpentine flow path to slow the flow of the elemental mercury-containing fraction from the inlet to the outlet; and a mercury accumulation area for collecting elemental mercury settling from the elemental mercury-containing fraction.

1 . A mercury recovery system comprising:
 a granulometric separator for separating a feed by particle size;   a centrifugal concentrator in flow communication with the granulometric separator for isolating and concentrating an elemental mercury-containing fraction of the feed; and   an accumulator tank for collecting elemental mercury from the elemental mercury-containing fraction, the accumulator tank comprising:
 an inlet in flow communication with the centrifugal concentrator; 
 an outlet; 
 a plurality of baffles defining a serpentine flow path to slow the flow of the elemental mercury-containing fraction from the inlet to the outlet; and 
 a mercury accumulation area for collecting elemental mercury settling from the elemental mercury-containing fraction. 
   
     
     
         2 . A mercury recovery system according to  claim 1  wherein the accumulator tank is Y-shaped and comprises:
 a first arm having an end region comprising the inlet; 
 a second arm comprising the plurality of baffles and an end region, wherein the end region comprises the outlet; 
 a bottom portion comprising the mercury accumulation area; and 
 a mercury outlet valve adjacent the bottom portion. 
 
     
     
         3 . A mercury recovery system according to  claim 2  further comprising a magnetic separator in flow communication between the granulometric separator and the centrifugal concentrator for processing the feed into a magnetic fraction and a diamagnetic fraction. 
     
     
         4 . A mercury recovery system according to  claim 3  comprising a water pump for providing fluidisation to the granulometric separator and the centrifugal concentrator. 
     
     
         5 . A mercury recovery system according to  claim 4 , wherein the granulometric separator comprises a first vibratory screen and a second vibratory screen, wherein the first vibratory screen is upstream of the second vibratory screen. 
     
     
         6 . A mercury recovery system according to  claim 5  wherein the first vibratory screen has a pore size of about 12 mm. 
     
     
         7 . A mercury recovery system according to  claim 6  wherein the second vibratory screen has a pore size of about 6 mm. 
     
     
         8 . A mercury recovery system according to  claim 7  wherein at least one of the vibratory screens is a high frequency vibratory screen. 
     
     
         9 . A mercury recovery system according to  claim 8  comprising a water-filled safety tank in flow communication with the outlet of the accumulator tank. 
     
     
         10 . A mercury recovery system according to  claim 9  wherein the system is mounted on a trailer. 
     
     
         11 . A method of recovering mercury comprising:
 (a) granulometrically separating feed from a source;   (b) centrifuging a fraction of the granulometrically separated feed to obtain an elemental mercury fraction; and   (c) channeling the elemental mercury fraction through a plurality of baffles defining a serpentine flow path to slow the flow of the elementary mercury fraction to facilitate gravitational accumulation and recovery of elementary mercury.   
     
     
         12 . A method of recovering mercury according to  claim 11  wherein step (a) comprises washing the feed with water. 
     
     
         13 . A method of recovering mercury according to  claim 12  wherein step (b) comprises fluidizing the granulometrically separated feed with water. 
     
     
         14 . A method of recovering mercury according to  claim 13  wherein after step (a) and before step (b) the fraction of the granulometrically separated feed is magnetically separated to obtain a diamagnetic fraction and a magnetic fraction, whereby the diamagnetic fraction is centrifuged at step (b). 
     
     
         15 . A method of recovering mercury according to  claim 14  wherein the magnetic separation step comprises fluidizing the diamagnetic fraction with water. 
     
     
         16 . A method of recovering mercury according to  claim 15  wherein step (a) comprises passing the feed through at least one vibratory screen. 
     
     
         17 . A method of recovering mercury according to  claim 16  wherein a first vibratory screen screens out feed particles having a size greater than about 12 mm. 
     
     
         18 . A method of recovering mercury according to  claim 17  wherein a second vibratory screen screens out feed particles having a size greater than about 6 mm.