The Patio and Cazo Process. 



.;; 



platform on one side on which 

 to pile the material to be treated. 

 Fig. 4. The front is closed vvitli plank 



in which there are six holes, 

 - 0.05 m. in diam., five of which 

 are closed with plains of wood. 

 _- invi „ M , P ;patio, Tliese serve to let off the slimes. 



3-- i!ON ON A.B, .//''-/ 



Jn front of these holes is a vertical wooden trough which carries 

 the slimes to an inclined trough, the bottom of which is provi- 

 ded with several mercury traps to catch any mercury or amalgam 

 that may be carried off. 



The lavadero is built directly against the patio, the pave- 

 ment coming up to its front wall. The material from the torta 

 is carried to the platform of the settler by a pair of steps built 

 on the platform side. The box is first filled half full with water. 

 Two men then get into it, while one man on the platform shovels 

 the ore into it. The men dance in the water, keeping it in mo- 

 tion with their feet, but keeping their hands out of it. The pulp 

 and water are added little by little, the pulp by a single spade- 

 ful at a time, until the slimes flow out of the top hole, while the 

 water is allowed to flow in only as fast as it flows out. The dis- 

 charge falls down the vertical to the inclined trough, over the 

 mercury traps and riffles, and goes from there to the settling 

 tanks. The heavier liquid below is from time to time discharged 

 by removing the lower plugs. The men are obliged to use a 

 great deal of discretion at this work. If they work too fast, there 

 is danger that some of the amalgam and mercury will be carried 

 off. If they work too slow, the heavier particles collect at the 

 bottom, and the small particles of amalgam sink through it 

 slowly or not at all. They know by experience from the diffi- 

 culty of moving their feet, when it is time to discharge through 

 the lower holes. They never allow the lower part of the box to 

 become filled. The amalgam is not removed until after the 

 whole of the torta has been washed, then the supply of water be- 

 ing kept up, the plugs are removed one by one and the amalgam 

 collected. 



In some districts where w T ood is cheap, the tub is substituted 

 for the stone box. The agitation in this is done with shovels or 

 poles from the sides. No better results are obtained, but the 



