New Zealand Gold Prospecting & Metal Detecting Forums Archive

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overdog		Posted : Sunday, 10 July 2011 5:04:12 PM(UTC)
Rank: Gold Ingot Medals: Groups: Registered Joined: 2/03/2010(UTC) Posts: 418 Location: nelson Thanks: 69 times Was thanked: 82 time(s) in 68 post(s)		Ok- If Im going fast and light and just using ribbed matting as a sluice box do I need riffles? If I classify my material down to say a quarter inch and feed it through slowly I cant see the advantage of riffles but I stand to be corrected...

kiwikeith		Posted : Sunday, 10 July 2011 5:45:49 PM(UTC)
Rank: Gold Ingot Medals: Groups: Registered Joined: 28/06/2011(UTC) Posts: 648 Location: hector Thanks: 359 times Was thanked: 230 time(s) in 154 post(s)		hi overdog personally i use rib rubber matting when just walking round the hills prospecting if good results then go back with aq box i have 3 boxes 500mm long each all fit inside each other so in turn they also all fit inside my pack sure bets carrying a box for 4 to 5 hours in the bush kiwikeith

Lammerlaw		Posted : Sunday, 10 July 2011 9:53:31 PM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 24/05/2011(UTC) Posts: 1,721 Thanks: 72 times Was thanked: 579 time(s) in 396 post(s)		Interesting - my two bobs worth here - Although some materials hold even the finest gold extremely well I have always thought it best to have riffles and the reason for this is that they tend to set up a small amount of turbulence behind them and this tends to clear a certain degree of sand and fine gravel so that the finer gold can settle down through to the bottom - if there are no riffles then the gold generally tends to go out the end with the gravel easier as there are no riffles to cause some turbulence to turn the gravel over and over as it goes down unless of course you have a much longer riffle box in which case it will eventually settle though to the bottom...hopefully. The riffles do not need to be large ones - on my lighter riffle box they are small pieces of angle iron about one quarter of an inch high only and extend only half of the length of the box - the top end being bare and onto which I shovel the gravel. The total length including the bare section is about four feet and the riffle section two feet I had never heard of the word classifier and have simply hand removed the larger rocks at source then shovelled the smaller rocks and gravel into the top end of the riffle box. Edited by user Monday, 11 July 2011 10:45:59 AM(UTC) \| Reason: Not specified

overdog		Posted : Sunday, 10 July 2011 11:36:26 PM(UTC)
Rank: Gold Ingot Medals: Groups: Registered Joined: 2/03/2010(UTC) Posts: 418 Location: nelson Thanks: 69 times Was thanked: 82 time(s) in 68 post(s)		I call it a classifier.My other half calls it "my best garden sieve you butchered you bastard". Ah well.Cant make an omlette without breakin eggs...

kiwijw		Posted : Tuesday, 12 July 2011 12:23:41 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 28/03/2010(UTC) Posts: 1,152 Thanks: 92 times Was thanked: 658 time(s) in 324 post(s)		G'day Overdog, You should have a riffle system of some sort. If you are pre classifying your material before throwing it down your box then you will be wanting a pretty gentle water flow down your box. Just enough speed & velocity to move the material down the box. Great for finer gold recovery. For your riffle system on top of your ribbed matting I suggest you use a gruntier expanded mesh. Weather you run the mesh all the way down your little box or just a couple of hundred mm. You want something to arrest the heavies & give them some where to hide & also to create a bit of eddy action to upset the material. This is a little highbanker I made that you shovel material into but the expanded mesh riffle system could easily be used in a little sluice box. Water flowing down over the expanded mesh Water turned off. Notice the black sands & very little other material on the down stream side of the expanded mesh. Great little riffle system. Mesh removed for clean up. Again notice the black sands. . This very fine gold was found at the very head of the box trapped in the small piece of ribbed matting under the expanded mesh in the 4th photo down . Shows how well it works. Happy hunting JW :)

kiwijw		Posted : Tuesday, 12 July 2011 12:53:54 AM(UTC)
Rank: Gold Ingot Groups: Registered Joined: 28/03/2010(UTC) Posts: 1,152 Thanks: 92 times Was thanked: 658 time(s) in 324 post(s)		I ment to mention that I generaly have three seperate carpets or two carpets & the first length of ribbed matting in any of my gold recovery systems. Weather it be a dredge, highbanker or sluice box. When I clean up I always wash out the very last carpet at the end of the recovery system first. This I hope has very little to no gold in it, because if it has gold in it then there is a good chance that gold could be going out the end of the recovery system. That isnt good & it means that adjustments of some sort need to be made. This is how I tell if my recovery system is working efficiently & to my liking & satisfaction. If not then I will make some changes. The 2nd or middle carpet should have some gold in it but most gold is usually in the very first carpet or even in the ribbed matting. Talking of classifying. In the highbanker above you will notice that in the top hopper, where the material is shoveled or dumped into, that the classifier screen has 10mm holes drilled in it. This means that no material greater than 10 mm will get through & go down the box. Which means I can have a gentler water flow for better fine gold recovery. Which was the aim for the fine gold I knew was in the material I was working. This is my sieve bucket set up I use when processing material down my stream sluice. Again the holes are 10mm so nothing bigger goes down the box. This was mainly because some little creeks here in the Coromandel have very little water flow & are unable to wash material bigger than this down the box without clogging the riffles up & stopping the sorting action of the riffles. Happy hunting JW :)

Free Fossicker Forster		Posted : Thursday, 2 February 2012 10:04:01 PM(UTC)
Rank: Gold Nugget Groups: Registered Joined: 30/01/2012(UTC) Posts: 35 Location: Oxford, New Zealand Thanks: 17 times Was thanked: 16 time(s) in 8 post(s)		Originally Posted by: kiwikeith hi overdog personally i use rib rubber matting when just walking round the hills prospecting if good results then go back with aq box i have 3 boxes 500mm long each all fit inside each other so in turn they also all fit inside my pack sure bets carrying a box for 4 to 5 hours in the bush kiwikeith Hi Kiwikeith Is the ribbed rubber matting you use the chunky car mat type or something else (I looked at one in Mitre 10 and it seemed quite heavy chunky stuff)? Do you use it on its own and then return with the box if you find something worthwhile? I will be getting around by bicycle in my next (second trip) and am trying to figure out effective lightweight equipment other than just a pan.