rock jaw-crusher, other rock crushers

[Richard Smith]

You have proved to be a remarkable font of knowledge.

Fancifully looking forward to tunnel-blasting rock (local is a very
hard granite) I looked to the "stemming". What you put put in the
collar of the drilled hole beyond the last charged blasting medium, to
effect a seal intensifying the blasting effect.

I know the one about if you try to press ceramic material down a hole
(or die or mould) it "bridges" and "locks". So I see "stemming" would
work in that way and is a good idea.
Then with a gravel stemming all that happens when it does "let go" is
a spray of grit - no heavy projectiles.

So that seemed a motivation to make a small jaw-crusher (best type of
crusher?) which can convert lumps of the granite into sharp gravel
about 4mm to 5mm size (?) to pack down the hole filling to the last
charge.

Whatever - it's a project.
I hear that a double-toggle crusher is best for very hard stone -
which this granite is. Giving a pure crushing action.
A single-toggle crusher with the eccentric shaft above the inlet for
the rock produces a combined crushing+shear as the moving jaw also has
up-and-down movement - which is reputed to increase throughput for
softer rocks but produce extra wear for no advantage on hard rocks.

Or does this not matter at small sizes?

I was thinking about 5"/125mm to 6"/150mm inlet capacity.
So quite a small machine.
Big rocks could be split with "feathers" - drill a socket, put in the
"feathers" and the wedge and split the rock.
We are not talking of huge quantities here.

Fanciful for sure. No-one at the mo. has a current blasting licence,
for a start...

But anyway - any experience?
I was thinking welded steel construction.
Apart from the jaws.
Cast very hard metal?
Cast "Hadfield Manganese Steel"?
Structural steel plate with welded hard-facing?

Regards,
Rich Smith

[Jim Wilkins]

"Richard Smith" wrote in message news:m14jecd...@void.com...

You have proved to be a remarkable font of knowledge.

Fancifully looking forward to tunnel-blasting rock (local is a very
hard granite) I looked to the "stemming". What you put put in the
collar of the drilled hole beyond the last charged blasting medium, to
effect a seal intensifying the blasting effect.

I know the one about if you try to press ceramic material down a hole
(or die or mould) it "bridges" and "locks". So I see "stemming" would
work in that way and is a good idea.
Then with a gravel stemming all that happens when it does "let go" is
a spray of grit - no heavy projectiles.

So that seemed a motivation to make a small jaw-crusher (best type of
crusher?) which can convert lumps of the granite into sharp gravel
about 4mm to 5mm size (?) to pack down the hole filling to the last
charge.

[What protects the wires to the blasting cap?]

Big rocks could be split with "feathers" - drill a socket, put in the
"feathers" and the wedge and split the rock.
We are not talking of huge quantities here.

[Wedges and shims or "feathers" is what I use to cut away granite protruding
into the paths around my house, which was crammed into a rocky hillside.

I've watched large granite boulders at a blasting site being broken up for
fill with a hydraulic "pecker" which is an oscillating single point chisel
mounted on a tracked excavator in place of the bucket. They said the
vibrations damaged the excavator so they used an old worn one for this job.
A single point carbide-tipped chisel is recommended for manually carving
granite too.

Apparently "Excavator" is also the British term. In German it's "Bagger".]
https://www.youtube.com/watch?v=VBMUvAUPTGM

Fanciful for sure. No-one at the mo. has a current blasting licence,
for a start...

But anyway - any experience?
I was thinking welded steel construction.
Apart from the jaws.
Cast very hard metal?
Cast "Hadfield Manganese Steel"?
Structural steel plate with welded hard-facing?

[Around here AR400 is commonly used for repairs and mods to construction
equipment.]
https://www.steelwarehouse.com/ar400/

[Richard Smith]

Current practice seems to be to use "Nonel" (non-electric) detonators.
Brilliant explanation at
YouTube channel
https://www.youtube.com/@mbmmllc

Video of "Opening My Gold Mine" series
"Opening My Gold Mine! Part 12: Last Drill & Blast"
go to about 23:39 / 36:20

* there's two delays - 0.3s at the clamp to pass on to the next shock tube
and 7s at the actual "blasting cap"

* the detonator goes to the bottom of the hole, so the blast propagation
is from deepest to near surface

* the "Nonel" tube conducting the shock/signal holds intact and does not
disturb the stemming or the blasting material it runs past

* the use of the delays is well explained in the video

Hope this is helpful


The "AR400" I think that is for excavator bucket lining and the like -
nothing like as hard as a rock crusher working face needs to be?

[Jim Wilkins]

"Richard Smith" wrote in message news:m14jecd...@void.com...

But anyway - any experience?
I was thinking welded steel construction.
Apart from the jaws.
Cast very hard metal?
Cast "Hadfield Manganese Steel"?
Structural steel plate with welded hard-facing?

--------------------
I bought proper material when building for paying customers, otherwise after
roughly estimating the demands I searched out what was available locally and
designed around it, usually in my head when I found it. This avoids minimum
ordering quantities and long waits. It helps a lot to pay attention to what
others have used to solve similar problems, and to own or have access to
machine shop equipment to modify stock shapes.

I depend on a medium sized vertical knee-type milling machine, a
thread-cutting lathe similar to a Myford, a 4"x6" horizontal metal-cutting
bandsaw and a pedestal grinder in addition to the welding equipment. The
mill serves as my drill press. For most jobs a good mill/drill would also
do. A larger bandsaw would be better, but what I have was enough to make a
hydraulic bucket loader attachment for my small tractor and a bandsaw lumber
mill, plus lab prototypes for aerospace projects and various custom
automotive tools. I have other equipment including a surface grinder, rotary
indexers and sheet metal shear/brake but those are the essentials. To
oversimplify the bandsaw and mill make the framework, the lathe makes the
moving parts.

To some extent the framework can be plate sawn or torched to shape and the
bolt and bearing holes done on a drill press, preferably after welding which
may shift nearby holes. Drilling two side plates clamped together makes the
hole locations identical if not exactly where intended. High tensile bolts
like US Grade 5 and 8 can serve as pivots though they aren't ideal for
diameter, length or surface finish. Machine tools give you many more options
and make putting bearing holes right where you want them and all parallel
(for the toggle linkage) much easier.

Here's a tungsten carbide hardface meant for rock impacts that can be
applied with acetylene:
https://tnfarriersupply.com/products/black-diamond-borium-rods

[Jim Wilkins]

"Richard Smith" wrote in message news:m1il2sh...@void.com...

The "AR400" I think that is for excavator bucket lining and the like -
nothing like as hard as a rock crusher working face needs to be?

----------------------------

It's a machinable high strength steel that I can obtain locally in small
cut-offs.
https://www.practicalmachinist.com/forum/threads/milling-ar-400-need-some-advice-please.239548/

Another is 5160 leaf spring stock, but it's limited in sizes. I made a D
step drill from O-1 drill rod to open a leaf spring shackle hole from 1/2"
to 5/8" that cut well enough after the second heat treating attempt. The kid
just had to lift his truck higher than his father's which was on a
commercial lift kit, so he had a higher lift kit fabricated and it came with
5/8" U bolts. As usual the answer was to call Jim for help.

If they are available wherever the H you are (Coober Pedy, Alice Springs?)
they might be strong plus tough enough for the toggle linkage and blade
bodies though not the cutting face which you suggested hardfacing.

[Richard Smith]

Notes from yesterday "YouTube'ing"...

vvvvvvvv

Notes from yesterday "YouTube".
Various manufacturers talking.
[Came across the eccentric wheel crusher]

Jaw crushers are tough - the reality. For primary crushing cone /
gyrating crushers have the numbers for throughput and the crushing
performance - but not that toughness. Much more vulnerable to
"uncrushable" debris, etc. - where damage sends up cost.

Impact crushers are found in bigger sizes.
Anyone wants a "one pass" large initial to fine final size.
Yes for small sizes / small operations.
Scale-up - still "one pass" - but wear goes against them, compared to
large crushing crushers.

Small-scale - gold prospectors sometimes improvise a chain-flail
impact crusher where deliberately nothing leaves the chamber until it
leaves with a throughflow of air as dust...

^^^^^^^^

For stemming you want a definite size distribution - a coarse (~ 4mm to
5mm ?) sharp grit - so much of above not relevant. Many "ore
extraction" applications - finer is better (?).

Heard of a roll crusher which apparently gives a lot of the throughput
close to the aim size (???).

[Leon Fisk]

On Thu, 15 Feb 2024 04:43:51 +0000
Richard Smith <nu...@void.com> wrote:

<snip>

>Heard of a roll crusher which apparently gives a lot of the throughput
>close to the aim size (???).

There are several old texts, compilations on Mining and such at
Archive.com. If you have any spare time nowadays :) For instance:

https://archive.org/details/miningscientific96sanfuoft/page/154/mode/2up

Came across them awhile back while searching for some old info...

--
Leon Fisk
Grand Rapids MI

[Richard Smith]

Thanks for that link.

At the mine yesterday someone told me

* he appreciated my links to YouTube videos on my webpage
http://www.weldsmith.co.uk/tech/minerals/240205_yt_goldmine/240205_yt_goldmine.html
"Opening My Gold Mine!" series
and had got up to 8 of the 17 of the series

* he and his father have a "hammer mill" - a high-speed (?) impact
crusher

* the output of that goes to some "California stamps" they made

* they have some 5% cassiterite (tin oxide) - ie. notably excellent -
ore to work which they obtained from a mine a few decades ago

So that's opened another conversation.

Rich Smith

[Jim Wilkins]

"Richard Smith" wrote in message news:m1frxs7...@void.com...

------------------------------------

My impression is that stamping mills have the advantage of being simple and
easily maintainable without needing a machine shop, perhaps only basic
blacksmithing equipment (or acetylene) suffices. When I study early 1800's
tech I look for what they needed to make it. Steam engines languished at a
primitive level for a century for lack of machine tools.

While not specific to mining, the forge that accompanied horse artillery is
a well described example of a self-sufficient portable metalworking
capability.
https://en.wikipedia.org/wiki/Traveling_forge
The original Army manual lists the equipment but not how it was used. In
addition to horseshoeing they had battle damage to their and other vehicles
to repair.

A modern version is the rather minimal gear blacksmiths carry to demonstrate
at fairs and festivals.

[Jim Wilkins]

"Richard Smith" wrote in message news:m1y1bm2...@void.com...

Jaw crushers are tough - the reality. For primary crushing cone /
gyrating crushers have the numbers for throughput and the crushing
performance - but not that toughness. Much more vulnerable to
"uncrushable" debris, etc. - where damage sends up cost.

Impact crushers are found in bigger sizes.
Anyone wants a "one pass" large initial to fine final size.
Yes for small sizes / small operations.
Scale-up - still "one pass" - but wear goes against them, compared to
large crushing crushers.

Small-scale - gold prospectors sometimes improvise a chain-flail
impact crusher where deliberately nothing leaves the chamber until it
leaves with a throughflow of air as dust...

^^^^^^^^

For stemming you want a definite size distribution - a coarse (~ 4mm to
5mm ?) sharp grit - so much of above not relevant. Many "ore
extraction" applications - finer is better (?).

Heard of a roll crusher which apparently gives a lot of the throughput
close to the aim size (???).

----------------------------
I've been waiting for and researching the question of what you need to build
such machinery, and haven't found good answers because it depends so much on
what you want/need to do, and how much size capacity you are willing to buy
new or can find locally used. Metalworking can become an expensive hobby
depending on the size, power and complexity of your designs.

[Jim Wilkins]

"Jim Wilkins" wrote in message news:uqsrip$11g2t$1...@dont-email.me...

I've been waiting for and researching the question of what you need to build
such machinery, and haven't found good answers because it depends so much on
what you want/need to do, and how much size capacity you are willing to buy
new or can find locally used. Metalworking can become an expensive hobby
depending on the size, power and complexity of your designs.

------------------------------

Here is a good example. Required horsepower and speed determine shaft
torque, and the dimensions of the appropriate shaft partly determine lathe
size, the spindle bore for long shafts and distance between centers for
short ones.
https://www.plantengineering.com/articles/relationship-of-torque-and-shaft-size/

Buying expensive new drive components can reduce or eliminate custom
machining, using salvaged ones increases it.

Likewise the distance between bearing bores that must be parallel determines
milling machine table size. Building larger with self-aligning pillow blocks
can bring fussy alignment issues and higher maintenance.