No offence Krum (OK a little bit), but it was doing my head in trying to read your informative posts without paragraphs, so have reposted with paragraphs if you don't mind:
"Hi Everyone. A gravity plant, or any metal ore processing method, is only as good as the particle size it is given from the crushing circuit. So if the crushing circuit was not providing a particle size small enough such that the tables, spirals, centrifuges or flotation could separate gold from dirt then all gold will be still attached to the dirt and will go to the tailings.
This is the same for all metal deposits. For any of the gravity machines to produce gold the ore needs to be crushed to the size of the gold nuggets. When a deposit is so nuggetty that you cannot drill holes close enough to correctly define the average nugget size, then its tough to correctly design the crushing circuit to that particle size. More crushing means more cost so they will not initially pay for such fine crushing.
Typically average nuggetty mines install a primary (jaw) crusher to take the ROM from say 300mm down to less than 100mm, then a secondary (cone) crusher to take that to less than 10mm or even 1mm. At 1mm and less there will generally be free gold (what size nuggets do their photos show?).
Within the gravity circuit, different machines operate at different particle sizes, but a table can separate out the vast majority of free gold down to say 50microns (micron = 1000th mm). Ball mills are generally installed between tables and cyclones (centrifuges) to break the tails from the tables down to say 100microns (0.1mm). The hammer mill is a way to crush down to fine sizes also. So its all about the crushing circuit not the separating circuit.
The hammer mill is crushing the ore to the right size to liberate free gold and then that feed is merely being provided to the table to separate it. The table (possibly Wilfrey) is already there as the first part of the gravity circuit or else its a Gemini table which is a precision table (looks like it from the photo) that is always in a gold room for any gravity circuit."
I have no question at all that once the material (cannot be called ore as is not JORC) reaches the processing plant that it can be successfully processed to extract the gold. They (if competent miners) can sort that out and Gekko know their stuff as long as the company provided Gekko representative material (which they would not have due again to difficulty in sampling).
The bigger problem is how to define (exploration) and then mine the material such that sufficient volume and grade material is delivered to the crusher then the processing plant.
Herein lies the major two problems:
How much money to send on close spaced drilling
and then what method of mining to use to get it out.
The reason there are hundreds of deposits like this around the world left for junior ASX explorer developers to get hold of is this exact conundrum and it really goes to the quality of the management (esp the Board Chair and CEO/MD). Experienced personnel can earn millions working for the majors and the majors must be into lowest cost quartile major mines etc. That's why only 1 in 100 of these juniors and mines ever make it, not because of the deposit, rather because of competence.
I note that a former poster noted Jeremy Grey as a gold expert - he's a broker so he is expert in gold finance not gold mining.
The more nuggety a deposit is the harder it is to analyse the grade. For instance if one tonne has a grade of 10oz (310gm) but its all in 1 single nugget then finding that nugget is tough. When one takes a sample from a tonnage to supply to the lab how do you know you got the nugget?
So your few grams will either analyse at zero or 10s of thousands of grams. See how risky it is - hence non JORC. The lab only digests or fire assays a few grams. One must sample out of the one tonne down to a few grams. Therein lies the problem analysing nugget deposits either by drilling, bulk sampling, head grade sampling, tails sampling etc.
One cannot treat these type of deposits like bulk low grade homogenous disseminated deposits (Super pit) where every few grams hold exactly the same amount of fine gold. The only way to sample these deposits accurately is to mine and process them. Its a complete fools game to say we got such a grade.
One should provide all the info (where is the JORC Table 1?) They should provide the total tonnes and grade fed in, the total tonnes and grade recovered, the total tonnes and grade that went to tails (all according to lab analysis). Then do a back calc of the tonnes and grade of both product and tails to see if it agrees with the feed. This is a mass balance.
Commonly nugget deposits mass balances can be out by many orders of magnitude. One asks why just provide the results of the apparent product without all this other necessary data? Where is JORC Table 1." Great info in these posts obviously from gold mining professionals Krum & Salt et al. Thanks.
SJB
OGX Price at posting:
3.6¢ Sentiment: Buy Disclosure: Held
), but it was doing my head in trying to read your informative posts without paragraphs, so have reposted with paragraphs if you don't mind:
