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Post by RKC on Nov 15, 2008 10:19:52 GMT 12
From: superjet1 Sent: 2/11/2008 1:38 a.m.
Hi
Would it be fair to say that anyone who starts out as a recreational dredger with more and more experiance can progress into a professional dredger or a production dredger? Experiance comes with time and effort. So starting at the bottom and working your way up gives us experiance!The dredges that have been built by dan float , suck and trap gold. I have seen this with my own two eyes.Yes the wheel has been invented but if everybody used that same wheel that was invented all those years ago it would be one bumpy and uncomfortable ride. I can only hope that we are not the OLD sheep that follows all the others. Its ok to think outside the square. I'm going to miss this forum so I hope you production and professional dredges enjoy your new forum with it's 10 members. I have learnt so much from this forum, thankyou. sad to see it go. Superjet
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Post by RKC on Nov 15, 2008 10:21:06 GMT 12
From: alluvial0 Sent: 2/11/2008 7:51 a.m.
Hi guys,
Please I am not on a witch hunt here. I think Dan does a fantastic job with the end result of his quality etc. I just think it is a bit naughty that he on sells his "trial" machines while he is "experimenting" with what works & what doesnt.Other wise I give him full credit for what he is doing. If selling to the public then they do need to be of very good performence both in suction & recovery. There is suction & there is SUCTION, There is recovery & there is RECOVERY. I think you get what I mean. I too am a recreational/hobby dredger & will miss this site also. But I can see where Rob is coming from regards to a forum for professional production dredgers only. He has given a sterling service to everybody who has posted or read posts on this site & the one before it. He has always maintained that this site was intended for the professional but has done his best to help out everybody. Maybe Dan as Rob has said, a site could be started by someone else for the needs of the recreational/hobby dredger & other general means of alluvial gold recovery outside of dredging. I am a bit of a thicko when it comes to computers & site set ups etc. You seem to have a good grasp of it & I would support you 100 percent if you wished to start such a site. May there be a run of gold at the end of your nozzle Regards Alluvial
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Post by RKC on Nov 15, 2008 10:21:43 GMT 12
From: groundhog Sent: 2/11/2008 8:04 a.m.
Hi All,
Your Right dredgeotago1 This is a fourm to throw ideas around from people who are experienced and not so, but where not here to pat anyone on the back and encourage all the time, this is a get real site, with honest opinions, the point alluvial was making is true. Let me go back a few years, Barry Clearwater knows how to make dredges, Why? because he did the most important thing of all, took patterns off proven small and large dredges, and sold them, but then he listened to all who went back to him with advice on how to improve, he took it on board, the dredges where great, and the everyone benefited.
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Post by RKC on Nov 15, 2008 10:25:08 GMT 12
From: RKCNZ Sent: 2/11/2008 1:03 p.m. G'day Matt ( flapperthermal), If you are intending to build your own suction nozzle, then there is no reason why you could not experiment with adding a "machined reducer" of the type Dan has referred to earlier. A "machined reducer" or tapered reducer, is made from a steel sleeve img.photobucket.com/albums/v172/Coochee/reducersss.jpg?t=1225582864 that is machined to produce an internal taper. You could then have a number of these tapered reducers made of different internal diameters to place at the outlet of the 180 degree bend of tube. And by experimenting with different sizes of tapered reducers you could then confidently decide on a size that best suits the pump you are using ... or if a reducer is actually of any use. But that's probably taking the long road and it might take so long it could keep you out of the water in a summer that is just about upon us. There needs to be a taper on most dredges somewhere between the pump outlet and the venturie outlet. And if I was making a suction nozzle I would not place the tapered reducer at the outlet of the venturie as Dan advocates. I would reduce the flow at the inlet to the 180 degree bend and run the 180 degree bend the same internal diameter all the way through for its entire length. A tapered reducer can be placed in a power jet img.photobucket.com/albums/v172/Coochee/HOT%20LINKED%20PHOTOS/ade56423pumpLLL.jpg?t=1225583418 to the same effect (if there is an "effect" that's actually an advantage) as in a suction nozzle. But most power jets and suction nozzles I've ever seen do not have a machined tapered reducer placed at 'the outlet of the venturie'. I have seen a few however ... on recreational dredges. Production dredges do not usually have a reducer placed at 'the outlet of the venturie'. On production dredges a tapered tube is usually placed at the inlet to the 180 degree bend on a suction nozzle and at 'the inlet on the venturie of a power jet'. Or, the tapered tube could be placed at the pump outlet. img.photobucket.com/albums/v172/Coochee/7f6nozzlenozzlKOK.jpg?t=1225582985 The placement of an internal machined tapered reducer at the outlet of the venturie seems to me that it might be a Kiwi thing that has possibly been used once on a Kiwi dredge and then copied by others. I'm probably not explaining it very well. If I had more time I could have done some diagrams ... maybe later. There is a reason relating to fluid dynamics that discourages me from placing a machined tapered reducer at the outlet of a venturie. I'm hesitant to mention it here as its essentially theoretical (theoretical as to how it would apply in a venturie) and I have never done any experiments myself to evaluate it (I'm not an experimenter, I'm an adopter of technology that works). But it does make sense to me. And if its something thats a problem, there is a solution thats simple. And the solution is probably worth doing anyway. If I get time I'll refer to the theory later this week, to see if it makes sense to anyone else here. I will need to do some diagrams to make it clear and my attempts to use the "Paint" program have not been particularly successful so far and has been too time consuming. I might be better to stick to pen and paper for any illustrations from now on. Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 10:26:56 GMT 12
From: Coro Sent: 2/11/2008 7:00 p.m.
Hi guys.
Just reading with interest the posts on nozzle operation and building dredges.
As you know I work with Dave Mac and his crews on all types of dredges. This year I was also involved in getting people into the water, and start dredging. The nozzle man. If you are serious about keeping your gold, you need to know what is happening at the nozzle. You can build the best dredge, have everything set up, but you will blow gold out the back due to not seeing, and in some cases up close, and I mean head right close to the nozzle, what is being sucked up. In other words it is possible to overload the nozzle, you end up with a heap of material in the box, overloaded, and the gold will migrate right out the back, before it gets the chance to settle. I see this all the time. People think that shoving the nozzle in the gravel with do the job. Nope, far from it. As you build a classification screen, you are in theory classifying the nozzle material before it gets to the sluice. It is all about production, but do not overload the nozzle!! The time spent in blockages will drive you to distraction. On the eight inch, the volume is something to behold, but, watch out, I have seen the dredge tender unable to clear the box fast enough because the nozzle man was a hogger, and all that gold is going right out the back, including the big stuff. If you are in shallow water, no less than three feet, then a snorkel may be ok, anything deeper and you need to be on the bottom with the nozzle. This way you keep the water clear, avoid plug ups, and allow the nozzle to work its magic.I read in one of the posts about Dave Mac´s books. That is a good idea. Read them, they are worth it. But in the mean time take you time if you are beginning this game. You might be disappointed re the gold you get, and the simple solution may be just the nozzle operation.
One of the best dredges I have operated, apart from the dredges that Craig Colt builds in California, is the Pro Line. They claim, no plug ups. I put this to the test. I used the 4 inch, and the 6 inch. They are right, no plug ups. The only time you get a plug up is due to overloading the nozzle, and then the plug is in the hose, easy to get at. They plug no where else. You can't blame the tools.
The secret to good continuous production is where the hose fits to the venturi tube. The hose actually fits on the inside, in other words you design an oversize venturi tube. Most plug ups occur at that junction if the hose is oversize, in other words, fits over the tube. Something to think about when building a dredge. I built my own here, a five inch. Five because I usually dredge remote places, and it is easier on the body humping all the gear in. I can really get the production moving, though always cautious on the amount going up the nozzle, especially when you have no tender or rock man. The only time that occurs is on the production six and eight inch dredges. I hope this helps guys. All the best out there. If any of you need info just drop me a line, no problems.
Cheers Coro.
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Post by RKC on Nov 15, 2008 10:33:32 GMT 12
From: RKCNZ Sent: 3/11/2008 9:13 a.m. G'day Dave ( : Coro ), Thanks for taking time (I know you are busy at present) to make a post! I believe that one of the most important and useful dredge innovations ever introduced, is the over sized power jet. And its worth acknowledging credit for the introduction of the oversize power jet. Oversize power jets were introduced on the Precision dredges that were first made in the late 1970s by the American professional dredger Pat Schofield. The introduction of oversize power jets is an excellent example of a useful innovation that came from an experienced dredger ... and could have only come from an experienced professional dredger.
The men who were responsible for introducing all of the innovations seen on most dredges these days have, unfortunately, been largely unacknowledged. And what they all have in common is that they were all experienced commercial scale (production) dredgers. There are disadvantages of using oversize power jets however, and because of the disadvantages oversize power jets are mostly used on Production dredges. More power is required when an oversize power jet is used! Therefore most recreational dredges smaller than 5-inch, do not generally use oversize power jets. Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 10:35:23 GMT 12
From: RKCNZ Sent: 3/11/2008 10:01 a.m. G'day, An extremely important consideration, that I have to mention, for anyone building a dredge that employes a power jet, is the positioning of the power jet. The power jet must fit up directly into the header box or diffuser (jet flair), and there should 'not' be any hose fitted between the power jet and the sluice box. There 'will' be blockages in the power jet on any dredge (except a dredge with an oversize power jet) and there must be a simple way for the blockages to be freed quickly. And the only way to free a blockage on a dredge with a hose between the sluice box and the power jet would be to take the clamps off each end of the power jet to get inside the power jet. This would obviously be extremely time consuming and inefficient. With the power jet placed so it directly fits into the header box, a rod img.photobucket.com/albums/v172/Coochee/HOT%20LINKED%20PHOTOS/OKOKbungOKOKOK.jpg?t=1225662084can be used to knock out any blockages. Its amazing to me that I even have to refer to something so basic that would be known to just about everyone with an interest in dredging. But to ignore referring to it might mean that someone building their very first dredge might just think that a hose could be placed between the sluice box and the power jet, with all the problems that would then arise for them (and time lost learning that its a mistake). Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 10:42:38 GMT 12
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Post by RKC on Nov 15, 2008 10:45:20 GMT 12
From: RKCNZ Sent: 4/11/2008 10:10 a.m. G'day Alluvial (alluvial0 ), Thanks for going to the trouble of taking the photos ... its most helpful. The reducer you show is a little differently set up to the one that is on a 3" suction nozzle I have. I would have taken a photo of mine except it is in storage at present and I don't have it to hand (I might try to get a photo of it later so it can be compared to the reducer in your photo). Also, I particularly liked the photo of the inside of your 4" power jet that shows the abrasion that results from moving a lot of rocks over time. You might be needing a new power jet fairly soon. Apart from the books by Dave McCracken that really should be read by anyone who dredges, Mr McCracken has written an article I would like to suggest should also be required reading by everyone with an interest in serious dredging. This artical www.promackmining.com/productiondredging.htmmust be the best article ever written about Production Dredging. And to add to what Dave (Coro) has said about blockages, this diagram img.photobucket.com/albums/v172/Coochee/Diagrams/HWS002.jpg?t=1225747781(and this diagram img.photobucket.com/albums/v172/Coochee/Diagrams/HWS003.jpg?t=1225747830) prepared by the Gold Dredgers Assoc of Australia, illustrate the point he made. And something worth adding to this thread, relating to nozzles, is this. www.49ermike.com/dc/dcboard.php?az=printer_friendly&forum=181&topic_id=2620&mesg_id=2623 Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 10:47:28 GMT 12
From: RKCNZ Sent: 6/11/2008 8:53 a.m.
G'day Tony ( groundhog ), I had a visit from Paul yesterday and he brought me up to speed on whats been happening down your way in the Lakes District (Queenstown). As I would have expected, the interest in dredging is increasing, as it is on The Coast, with a lot of men presently constructing dredges ready for the comming summer. But from what Paul has told me they are all making the classic mistakes that beginners always seem to make ... such as going for 3-inch or 2-inch dredges and actually thinking they will get gold, and they are nearly all experencing difficulties sourcing dredge parts, and ... they lack the know-how to make a workable dredge. There really is a market developing for sales of a recreational dredge. Might be the chance for someone to make a 5-inch dredge to supply beginner miners ... I can only see an ever increasing interest in men who want to start dredging and take advantage of the increasing gold price which can only go even higher. I've been discussing with Paul that we might both work togeather this summer to test his claim on the Shotover, by doing a througher sampling program over the full extent of the claim. Should be and interesting exercise if I can find the time to get down to Otago this summer! Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 10:48:52 GMT 12
From: groundhog Sent: 6/11/2008 1:54 p.m.
Hi Rob,
There is certainly a lot of interest in the gold mining sector, was talking with Barry the other night about making dredges again. The only thing that really concerns me with this is that we might have a pattern forming here in the respect of what happened years ago, not many people with dredges have claims, and a lot of people are not aware of the rules and regulations, hence some people dredge in areas that are in the public eye drawing attention to and actvating all the issues that date back to the early years of trying to stop people dredging without a Claim, This can and will happen if more care of where to dredge is not taken into account, education is a must on this matter. Unfortuanly to claim an area off now is almost impossible, with vast areas being pegged off by big mining companys, thus shutting out the small miner. Pointing out the faults in the system to the mines department only falls on deaf ears, which leaves most average Kiwis, who would like to have a go at dredging nowhere to " LEGALLY" Dredge........
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Post by RKC on Nov 15, 2008 10:49:52 GMT 12
From: alluvial0 Sent: 6/11/2008 10:01 p.m. G'day Rob,
Hasnt the shotover been cleaned out by the Ryan Brothers & then L&M who carried on from the Ryan Bros. Or are you talking about a side creek in the general area of the shotover as a catchment?? I am off down to Queenstown tomorrow for a couple of months with my 4" dredge. Timed the weather pretty bad though. Alluvial
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Post by RKC on Nov 15, 2008 10:51:32 GMT 12
From: RKCNZ Sent: 7/11/2008 10:17 a.m. G’day Tony ( groundhog ), Even these days the possibility remains that there could be a repeat of what happened in the late 90s, when the Otago Regional Council started chasing dredgers around Otago. It would only take a hobby dredger to turn up at Arrowtown at Christmas and wander down to the Arrow, and put his dredge in the water at the Fossicking claim, for it to explode and become an issue again. I believe, the difference between what’s likely to occur these days compared to what occurred in the late 90s, is, for one thing, that the ORC would not be so inclined to be readily spending money on helicopters to chase down dredgers in the back country. With all the “other peoples money” they are spending on monuments to themselves www.odt.co.nz/news/dunedin/5347/orc039s-answer-sydney-opera-house and the millions they are losing from their “investments” in overseas stock markets, there would be little left over for helicopter hire ... I suspect (or hope). You would think that anyone who intends to take up dredging for the first time would make themselves aware of all the "rules and regulations" ... and the advantage these days is that its all accessible on the Internet by going to the Crown Minerals web site and the Otago Regional Councils web site. During the 90s there was a lot of naivety among the Kiwi dredgers about what they were entitled to ... that, I hope, has now changed. I don't entirely agree that "Unfortunately to claim an area off now is almost impossible, with vast areas being pegged off by big mining companies". Mining companies are not interested in the live rivers and permission may/should be given to peg a river dredging claim over an area where a prior Exploration Permit exists. The way to go would be to apply for a Mining Permit and then deal with issue as/when it arises.It is technically possible to "peg" a "claim", but the most significant disincentive is still the expense involved to get a "claim", and the Resource Consents, granted. img.photobucket.com/albums/v172/Coochee/GoldMinersDespairAAA.jpg?t=1226006825 img.photobucket.com/albums/v172/Coochee/P1010039.jpg?t=1226006890 img.photobucket.com/albums/v172/Coochee/NZGOLD_G_TRE009.jpg?t=1226006966 img.photobucket.com/albums/v172/Coochee/NZGOLD/31cec0de.jpg?t=1226007289 Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 10:58:21 GMT 12
From: RKCNZ Sent: 7/11/2008 10:52 a.m. G’day Alluvial (alluvial0), Yes, the Shotover has been well and truly “ cleaned out by the Ryan Bros and L and M Mining”. But ... that’s no reason why we should not to sample it as all the nuggets went straight through L&Ms trommels and back into the river. And because the excavators made all the river gravel lose, all the nuggets went straight to bedrock after one or two Spring floods. The claim I mentioned in an earlier post is on the Shotover main river img.photobucket.com/albums/v521/NZGOLD/Shotover%20river%20goldfield/NewImage9.jpg?t=1226011290up at the Sandhills cut img.photobucket.com/albums/v521/NZGOLD/Shotover%20river%20goldfield/NewImage8.jpg?t=1226011215 . L and M Mining went right through that section of the Shotover … not even skipping sections, like they did further down the Shotover when they skipped over a few rapids such as the Mother rapids (very good gold still in those rapids). The 'possibility' remains that payable fine gold still exists in the Shotover river … when the means of mining is by suction/eductor dredging! The efficiency of suction dredging can make what would be regarded by many miners as non payable ground, payable. We have some theories about where and why good gold remains in a river that was previously gone over so thoroughly by floating trommel plants fed by an excavator. But to confirm the theories we need to do some extensive sampling with production dredges over the entire length of the claim. And to carry out the sampling so it conclusively proves that payable gold remains, requires expertise in sampling techniques and dredging experence. And to do the sampling to the required degree of efficiency, requires the use of a dredge that is of a very good design (and a dredge bigger than 6-inch). However, the dredge is not fully constructed yet … hopefully it will be by the time high summer arrives in Otago. Regards, Rob (RKC)
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Post by RKC on Nov 15, 2008 11:00:06 GMT 12
From: groundhog Sent: 7/11/2008 3:47 p.m. Hi Rob, The rules have changed a lot in the mines department, once a mining company has blanket peg an area, you CANNOT put in for a claim of any sort. You have to go to the mining company, show them the small area you wish to dredge and ask them if they can relinquish the area out of there lience, there is no other way, thats why the small Miners association are kicking up such a fuss. I have been dealing with an Australian Mining company, and do you think they want to play ball, propper Bast...... when they say No thats it. But Rob, if you have another way Im not aware of I would very much like to hear it, I cant find any other way around it with the new Rules the mines department have passed.
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