L David Michaud

About David Michaud

Since 1993, when he obtained his Mining Engineering Degree from Queen’s University, David has acquired experience in operating roles including many years in post-commissioning operations troubleshooting. Mineral Processing and Metallurgy has become a core strength and passion for Mr. Michaud. Learn more at https://www.911metallurgist.com/about-us/

Ball Mill Circuit Classification System Efficiency

Fines may be defined as any material smaller than a specified product size, and “coarse” as any material that is larger. The target 80 percent passing size of the grinding circuit product is a convenient reference point, as it is often used to express the grind size objective. This size is close to the modal value of typical size distributions of ground material, and also roughly approximates the classifier cut size.

The effectiveness of the fines removal system depends on the transportation of material to the classifier. It also depends on the ability of the classification equipment to remove the fines that are presented to it from the circuit, and to return the coarse material to the mill. Immediate and perfect sorting action would result in a circuit product size distribution dependent only on the material fracture characteristics (Austin et al, 1984), and avail the maximum possible amount of mill volume (and applied power) for the breakage of coarse particles. The fraction of fines in the mill hold-up (the “fines inventory”) may therefore be taken as a direct measure of the lack of the system’s fines removal effectiveness. Its complement, the “coarse solids inventory” represents the fraction of the mill volume ….Read more

Underground Mining Geology

In the previous topic we learned that the economics of mining is particularly related to the amount of ore that can be produced and the amount of waste rock that must be moved. That makes underground mining particularly suited to structurally compact ore bodies with high grade ores which don’t require an extensive network of access tunnels through worthless rock and which don’t involve large qualities of gain being brought to the surface with the valuable ore and deeper deposits where excessive depth of overburden makes the costs of accessing the ore prohibitive. In this topic, we will take a look at those situations in some more detail. Mineral and oil deposits come in many different forms and contain many different types of minerals. A full consideration of the geological origin of oil deposits is well beyond the scope of the current course. In this topic, we’ll only consider those mineral deposits which are relevant to our discussion of underground mining.underground mining geology Classifications of mineral deposits can be formed on many different basis. These include the genetic geological origin of the deposit that is how it is formed, the minerals it ….Read more

Underground Mining Methods

The choice of an underground mining method depends on a range of factors and these include; the size and shape of the deposit, the orientation or slope of the deposit, the depth of the deposit, geological structures, characteristics of the ore and the surrounding rocks and issues with gas and water. In combination, these factors allow us to determine an appropriate arrangement and sequence for mining operation but before going on to look to see how they combine to mine specific geological ore bodies, let’s have a look and familiarize ourselves at the different basic elements of an underground mine and there basic purpose. underground mining methods (1)

Before an underground deposit can be mined it must be accessed. Access to an underground ore body is achieved through a combination of shafts which are vertical tunnels, drifts and drives which are horizontal tunnels and declines and ramps which are inclined tunnels. Access provides for getting people and equipment to the ore body, getting mined ore and waste out of the mine, ventilation and emergency egress and getting waste and tailings in to backfill the mine.In general the access arrangement for people, equipment, ore ….Read more

Open Pit Mining

open pit miningopen pit mining 003open pit mining 001 In model 1 with Stephen, and in the previous topic, we saw that the geological aspect is one of the main factors that affect the design of a surface mine. What are the characteristics and other aspects should be taken into a code for the final configuration of the surface mine. Between them, we have to take into account of the safety, economics, and the recovery of the material.open pit mining 002

In the next topics we will see how all this could be achieved. But before that, let’s have I look at which are the main physical elements that make up a surface mine. When we create an excavation with the purpose to mining a deposit, the excavation is called, pit. The pit is a hole in the ground with sloping sides leading to the pit floor. The waste from the hole in the ground is placed on a dump. In a later stage, we will discuss what ….Read more

Open Cast Mining Advantages

In the previous topic, we saw which are some of the advantages that can make the surface open pit mining methods superior method compared to the underground mining. However, underground mining has its own advantages. And finally, the ultimate decision to mine from the surface or from underground comes down to the specific characteristics of the deposit. In particular, mineral deposits can occur in very different forms and they may contain a very wide variety of minerals.

open pit mining pros and conshttps://www.thinglink.com/scene/484765116097626112

In this topic, we will try to see which are and which are the characteristics of the deposits that are most suited for surface mining. Generally, it’s easy to think that mineral deposits that are already outcropping to the surface or lying at very shallow depths from the surface are easily extracted using a surface mining method. From the geological point of view, we have several mineral deposits that are in these conditions and that can be extracted completely from the surface, and that we can find also some deposits for civil constructions.

For civil construction, we can consider the deposits of sand, clays, gravel, rocks, and all of the ….Read more

Stop Mining Method

Stop Mining Flat Deposit

In the previous topic you were introduced to the different methods adapted to mine underground deposits. Well the basic elements are common to most underground mining operations, there are many variations in the theme. In the next three topics we will see how these methods can be adapted to mining deposits in different geologic situations. stop mining method (1)Let’s start by looking at stope mining in flat deposits. In the previous topic we were introduced to strata form and stratabound deposits which are common from minerals such as coal and iron ore. Where these occur the flat deposits that is sloping at around less than 20 degrees. These lend themselves to a particular stall called stope mining. What is common today is that the mining progresses from one part of the deposit to another mostly within the same plain. What is different is the size and the shape of the pillars used to support the roof and the methods used form them. Stope mining and flat deposits are distinguished on the basis of the stall or the stake being merely described as rooms, stalls, or boards in ….Read more

Mining Engineering & Mineral Exploration Economics

Mining Engineering is a lot about applying the knowledge of applied science and Engineering Mechanics to the successful extraction of useful geological resources. So in this first module we will overview the mining process in its entirety and identify those aspects which are the realm of the mining engineering. Then in the next three modules we will look at the specifics of mining engineering in greater detail. We will devote this first topic to identifying the steps in the mining process, and to introducing the terminology that used in the mining industry and that will be used throughout this course.

The mining process begins with finding a new mineral deposit and it ends when the mine is abandoned after it has been rehabilitated. Basic steps in the mining process are:

  • Mineral exploration to find a new deposit.
  • Economic Assessment of the deposit to a prices viability mine design which we’ve a safe, stable and financially viable operation. This is the main job of the mining engineering.
  • Image resultEnvironmental impact assessment mitigations
  • Beneficiation of the mining product
  • Handing on the mining products and wastes
  • Mine closure in site remediation

These headings services as the list of ….Read more

Rock Mass & Rock Matrix – Discontinuities

rock mass matrix (1)In this topic we will discuss what constitutes a rock mass and its relevance for engineering.in this photo, you can see a rock face and what is quite clear is that the rock is not homogeneous. Compare to this specimen of sandstone, which has a uniform color and no clear planes crossing it. In contrast, the photo shows many lines, vertical lines and horizontal lines. Vertical lines are simply referred to as discontinuities and discontinuities fall into two categories. They’re called faults if some relative movement has taken place. As we can see on this second photo, you can see that the stripes of color do not align from left to right. There’s been some vertical movements that offsets the stripes. This happens along the faults. If there is no relative movement observed, these are typically called joints.

The rock mass, as a whole is a combination of blocks of homogeneous rock, also called rock matrix, or intact rock separated by discontinuities. The rock matrix has certain properties depending upon its mineralogy, origin, the degree of weathering, and the discontinuities would have different properties.

rock mass <a href=….Read more

Mining Geomechanics – Stress & Strain

We’re going to introduce in this topic the two key variables required to define the fundamental behaviour of materials. These variables are stress and strain.

In many engineering applications it is required to assess how a structure deforms or behaves under a load. Making such an assessment requires some knowledge about the material constituting the structure itself. For example you couldn’t sit on the chair made of rubber. You need a stronger material like hard plastic or timber. So when it comes to characterising a material there are two questions we need to answer. One is, how much does a material deform under a load? The second questions is, how much load does it take for the material to break? And to answer these questions we need to define stress and strains. Let’s see why with an experiment.

Strain Experiment

mining geomechanics stress & strain (2)

We take a short rubber band and we’re going to place this rubber band in intention. We start by measuring its initial length, which comes to 54 millimetres and we place weights on this hanger to stretch the rubber band. It now stretched to 62 millimetres. Let’s ….Read more

Mining Exploration Process

online-geology-courseHow Explorers develop an exploration strategy, how they develop an exploration model and design an exploration program and select the optimal exploration tools to carry out that program. As usual of the talk will end with a series of learning points from this talk.

 

There are two fundamental truths about the exploration industry; the first is that most exploration programs are doomed to failure. It’s been estimated that only 1 in 5000 or even 10,000 of all prospects will eventually be shown to halt deposits that can support a viable mining operation. Therefore the odds are that the vast majority of exploration programs will end up with nothing to show for the dollars they’ve spent. The second fundamental truth is that most Explorationists has more ideas than they have funding to test those ideas. These two truths mean that simply playing the odds and drilling hundreds of targets is a short cut to financial ruin. If they are able to be successful, companies need to develop their explorations strategy with a huge amount of thought and research. The old adage of failing to prepare is preparing to fail holds particularly true to the exploration industry.

….Read more

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