Company Report: Promimex

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MIMEX

TECNOLOGIAS S.A. DE C.V.

Company Report PromiMex

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View From the Top Felipe Palma General Manager | Promi-Mex

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View From the Top Rodrigo Morales Technical Manager | TecProMin

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View From the Top Francis Pitard President | Francis Pitard Sampling Consultants

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Analysis Solution to Uncertainty in Metallurgical Analysis: Part 1

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Analysis Solution to Uncertainty in Metallurgical Analysis: Part 2

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Spotlight Not Every Sampling System Is Biased

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Analysis Promi-Mex: Representative Sampling Systems Equal Productivity

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Analysis Promi-Mex’s Experience in Chile: Mineral Sampling Towers

VIEW TOP Promi-Mex | Company Report | 4

from the

Q: What is Promi-Mex’s main added value?

A: Our portfolio is very complete. We are still missing flotation cells and certain milling applications, but other than that, we have a full solution for processing plants. Nevertheless, it is not enough to have a robust portfolio of manufacturers. Promi-Mex has gone beyond that to meet the need for highly-qualified engineers. Our team has a great deal of experience in mining and can select the right equipment from our portfolio, install it and operate it. We are also capable of installing all necessary infrastructure.

Our main guideline for providing the best technical service is to have a complete knowledge of the plant. We discover what the client needs and offer a solution to a real problem, rather than creating an artificial problem that suits our solutions portfolio. The strategy is to identify opportunity areas. This can be challenging because many times plants are run by engineers who are immersed in their own processes and lose some perspective. Nevertheless, once we detect an opportunity, we devise an idea and present it to the client with a clearly defined ROI. When the idea is approved and the budget negotiated, we then build the project, using equipment from our 12 manufacturers in our portfolio. An important service that we offer is training the clients’ personnel thoroughly after the project is completed. We also deliver a weekly report to management and to the manufacturer of the equipment we are installing. Transparency among all parties is key.

Felipe Palma

Q: What challenges have you run into when implementing improvements at processing plants?

General Manager | Promi-Mex

A: Many times, the client already has an installed infrastructure and it is hard for the engineer in charge to change the client’s mind.

They tend to stick with whatever has guaranteed production in the past. “If it is still productive, why change it” is the prevalent philosophy. Our engineers have to be able to speak the same

Promi-Mex: Representative Sampling Systems Equal Productivity

language as our clients’ engineers and advocate potential improvements. Once we implement our improvements, the benefits become evident quickly and everyone starts to cooperate.

Q: What benefits do your sampling systems provide to a minerals processing plant?

A: Tecpromin’s sampling systems are our core business for products and integral solutions. The purpose of a sampling system is to take a representative sample of a certain material that needs to be analyzed. Tecpromin’s systems meet national and international standards and operational requirements. They are used for keeping the metallurgical balance right. In Mexico, I believe there is no other equipment that can offer the level of representation that Tecpromin offers. The fact that they follow international standards means that any auditor in any part of the world can use the samples and verify if they qualify.

The point of keeping a precise metallurgical balance is to know how much ore is being processed and how much is being sent to the tailings pond. There are different sampling systems and they are installed in different points of the plant. We installed a sampling

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system at the tailings discharge point of a plant in Northwest Mexico. The plant’s superintendent no longer has to worry about the representativity of the sample there: it is 100 percent representative. This offers better tooling to improve the overall process, based on the results of this accurate system.

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from the

Q: How do TecProMin’s sampling systems fit into its product portfolio?

A: We have our own business lines, resulting from our own engineering, knowhow and design. Prominent within those lines are our sampling systems. We do not sell “off the shelf” equipment; rather, we provide and integral technological solution system. We have added technological value to our portfolio with some the products of the companies we represent or have joint venture agreements with. We integrate these solutions and produce a complete package. Each of our engineering and technological solutions are tailored to our clients’ needs.

Q: What issue do your sampling systems address?

A: The main problem our sampling systems solve is common to all mining operations in the world: metallurgical accounting, commonly known as metallurgical balance. In a financial institution, inventories are carried out to know precisely what resources are coming in and going out, so that when a balance is presented, the net balance is zero. The same applies to mining. In this case, the main factor is the commodity that the operation produces.

The company needs to know within a reasonable degree of accuracy, what amount of the commodity enters the processing plant, how much will be processed and how much is lost during

Rodrigo Morales

that process. If this metallurgical accounting is to be representative of reality, it has to be done by means of a sampling system that is as much as representative as possible. The quality in terms of representativeness of the sample that is taken to the laboratory for

Technical Manager | TecProMin

analysis has to be as high as possible. A poor sample, statisticallywise, obscures reality. For instance, if the lot has 2 percent copper, but the sampling system is not adequate, the laboratory can conclude that there is 0 percent copper. Of course, the sample is dependent on other factors but if the sample is not statistically

TecProMin: Standardized Sampling for Total Confidence

representative, the whole process becomes vitiated.

Q: What are the key requirements that TecProMin’s systems fulfil?

A: Among other requirements, the sample must be equiprobabilistic. This means the probability of the sample that is taken from a lot has to be representative of the actual lot. To guarantee that, sampling systems have to comply with a series of technical standards that are regulated internationally, as well as updated sampling theory. Our sampling systems comply with these standards and with all statistical best practices, including Pierre Gy´s modern theory of sampling.

The process can be understood as a black box, where you need to know the inputs and outputs precisely, so the metallurgical balance makes sense. When a mineral producer sells its product to a client, the former has to know exactly how much valuable content is being sold. To do that, a proper sampling is required. The seller, who may be a copper producer in Mexico, may argue as an example, that his product has 30 percent of a value metal content. But the buyer, who can be a smelter in Japan, will also take a sample. If that sample says that there is 29 percent copper content in the product,

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then the divergence must be discussed. The first point for clearing the matter up will be the sampling method used. If any of the two parties does not have an auditable method — one that complies with all requirements, standards and theory— then it will not be able to argue the case and will probably lose in the transaction.

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from the

Q: Why is it important that people in the mining industry be familiar with the Theory of Sampling?

A: The economic impact can be massive if sampling is not done correctly from the very beginning of the process. At the very least, you need to have a foundation on the basics of the Theory of Sampling: what to look for, what can go wrong, how badly it can go wrong. That must be clear in the minds of management when they make important decisions, such as what sampling equipment to purchase. If you look at the world market of sampling equipment, a large majority of the available equipment will not do the job properly. Again, the origin of the problem can be traced back to a deficient knowledge of the Theory of Sampling that is not taught at universities. Most manufacturers do not understand the problem and manufacture machines that are flawed by design.

Miners should choose equipment from one of the very few leading manufacturers in the world, including TecProMin. These companies have made the effort to become educated and test their equipment properly before selling it.

A good place to become educated about the Theory of Sampling is my book, which is in the third addition since its publication in 1988. It is written in such a way that the reader can teach himself, with patience and discipline. It can be studied in as little as six months. Of course, teaching courses is also

Francis Pitard

important, as I do at the Colorado School of Mines every year.

Q: What was your role in developing top sampling systems with TecProMin?

President | Francis Pitard Sampling Consultants

A: In 2000, with almost 20 years of experience, TecProMin decided to improve its standards. It had Codelco’s backing, because the company was interested in fixing certain sampling issues at their plants.

Theory of Sampling Key to Effective Processing Plants

The main problem started with the design of sampling equipment and sampling methods. There were fundamental flaws there. I led more than 20 courses for Codelco in which TecProMin was always involved. Codelco paid for all the R&D. The trial and error process lasted for three or four years. Today, TecProMin has the best sampling equipment in the world. The success was in great part due to the involvement of a big player like Codelco.

Once upper management was convinced, we were able to quickly change sampling systems in the company’s processing plants, often without the support of the superintendents. It is hard to change habits at that level, but once our sampling methods and better sampling systems were in place, the superintendents came on board. In over a period of 10 years, we had all of Codelco’s operations equipped with proper sampling systems.

But the battle is not over yet. The next step is to develop a companywide care and maintenance culture. It is not enough to have the best sampling systems. There are many

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things that can go wrong if equipment is not carefully inspected and cleaned every day. You cannot just install an automatic sampling system, clean it once a week, and provide maintenance every six months. It must be a daily, constant practice.

Promi-Mex | Company Report | 7

Solution to Uncertainty in Metallurgical Analysis: Part 1 Sampling systems experts Promimex and TecProMin, the Zacatecas’ Mining Cluster and Mexico Business Publishing joined forces to organize a two-day e-course on applying the Theory of Sampling for achieving optimal metallurgical balances.

The course was delivered by world-renowned expert Dr. Francis Pitard.

The e-course had its first session on Aug. 19. Dr. Pitard started off by surveying some basic elements of the theory of sampling. Dr. Pitard focused first on small scale variability. He pointed out that sampling technicians introduce all types of variability that will confuse them if it is not well understood.

To keep small scale variability under control, Dr. Pitard advised to start by optimizing the sampling protocol. This includes geologists orderly dealing with in-situ nugget effect. It also involves fundamental sampling errors that are negligible for base metals but are key for precious metals. Moreover, the sampling protocol must take grouping and segregation errors into account: different metals have different densities and properties.

After optimizing the protocol, one has to implement it. Important aspects of this include increment delimitation errors, increment extraction errors and increment weighing errors. Dr. Pitard went over the main ways to minimize these errors. Lastly, it is important to preserve the sample’s integrity. To do this, Dr. Pitard mentioned the importance of increment preparation errors and of contamination, loss, alteration, human, fraud and sabotage error. Moreover, he highlighted the analytical error, which includes aspects like scope versus principle, dissolution technique, contamination and losses and proportional interference. Dr. Pitard also explained variability on a large scale.

He underscored the relevance of interpolation errors, periodic errors and increment weighting errors.

Once the main sources of bias had been explained, Dr. Pitard said that one has to prioritize which ones make the most sense to eliminate first. He advised to set up a matrix and establish priorities. The matrix should specify the effect of a given problem vs the cost of fixing it. Dr. Pitard continued his lecture by explaining how most sampling equipment currently in the market is biased by design. This is not due to fraudulent intentions, he said. The problem is that engineers are not trained in the Theory of Sampling. Therefore, they build machines that are flawed by design. He noted that there are a few good manufacturers in the market, including Santiago de Chile-based TecProMin. When selecting a sampling system provider, Dr. Pitard said it is important to have the following points in mind. First, reliable sampling for metallurgical balance cannot be done on coarse material, so the most vulnerable area is the sampling feed that goes into the plant. Second, one must know the heterogeneity of the constituent of interest: mineralogical studies, heterogeneity Read the complete article More about this topic

tests and relevant geological information are key to this end.

Third, one has to select equiprobabilistic sampling systems and correct mechanical sampling systems.

Promi-Mex | Company Report | 8

Solution to Uncertainty in Metallurgical Analysis: Part 2 Promimex and TecProMin, the Zacatecas’ Mining Cluster and Mexico Business Publishing joined forces to organize a two-day e-course on how to apply the Theory of Sampling to achieve optimal metallurgical balances. The course was presented by world-renowned expert Dr. Francis Pitard. Its second session on Aug. 20 focused on sampling bias. Dr. Pitard started his lecture by noting that many people think that if they can quantify the sampling bias, they can then decide whether they can accept the bias in their operations. Unfortunately, in sampling, there is no such thing as a constant sampling bias. This is particularly the case if there are several superimposed sampling biases in the sampling system. Rigid adherence to sampling correctness will save time, money and effort. “Sampling is not gambling,” he said.

Dr. Pitard went on to emphasize that thinking that biases can be quantified is a devastating misconception. Upper management tends to misunderstand this and think that quantifying bias can solve the problem. However, this can result in massive economic losses. Dr. Pitard underscored that if the sampling system is not correct, it is futile to test the bias. This is partly due to the fact that it is likely that there are many biases, not only one. That makes adequate quantification practically impossible.

Some of the main biases metallurgists run into are correctness, increment delimitation errors, recovery problems, preparation errors and increment extraction errors. Dr. Pitard said that the only logical strategy to eliminate them is prevention. Engineers should become educated in the theory of sampling. Furthermore, management should have zero tolerance for suboptimal sampling systems and realize that 75 percent of those in the market are suboptimal. Finally, there has to be a company-wide culture that furthers statistical understanding of sampling biases variability.

Dr. Pitard approached two key problems related to sampling biases. First, all sampling biases are created by some form of segregation in the stream, which the system cannot take into account. However, the stream is not segregated uniformly, resulting in inconstant sampling biases. The second problem has to do with the confusion between sampling and analytical biases. While the former is inconstant, the latter may not be so. Sampling biases are messy and involve precision issues: even if the average bias is small, its consequences can be huge.

Dr. Pitard’s conclusion was that, while it is possible to use a correcting factor for a biased analytical system, it is impossible to do so for a biased sampling system.

Nevertheless, there are times when one is forced to work with a biased sampling system. In that case, one has to decide how much allotted variability is reasonable for the Fundamental Sampling Error (FSE): the error generated by the mass of the sample taken.

According to Dr. Pitard, the answer depends on data quality objectives. These vary depending on different points of view: grade control engineers, exploration geologists and metallurgists Read the complete article More about this topic

will have different answers, for example. However, all of them agree on something: the FSE is not their only problem. They also have to deal with residual sampling and analytical errors.

SPOTLIGHT

Promi-Mex | Company Report | 9

Not Every Sampling System Is Biased To run flawless processing plants, carrying out unbiased metallurgical accounting is of the essence.

However, most sampling equipment in the market is biased by design. Manufacturers are hardly ever trained in the Theory of Sampling. Only a handful of manufacturers in the market, including Santiago de Chile-based TecProMin, are trained in this discipline.

Sampling systems are a set of equipment and elements that work together to obtain representative metallurgical samples. To eliminate bias, the design of a sampling system has to comply with the Theory of Sampling and international standards. Furthermore, the manufacturer must include a series of additional considerations, mainly in terms of maintainability, reliability, automation and constructability. Personal safety needs to be integrated into the station’s design, as well.

The components of the systems can be divided into two main groups. The first encompasses equipment that deals with increments of a sample or lot in each stage of the metallurgical system. The second includes auxiliary or complementary equipment that is not directly associated with taking increments for sampling purposes. A key aspect to consider is that equipment must not only be well-designed according to the considerations indicated above but also arranged and located correctly within the system. Distances and inclinations directly influence the material’s transfer speeds. Not getting this completely right may result in partial losses of the sample’s elements. It can also lead to segregation Read the complete article More about this company

by sizes and densities that lead the system to have a varying bias that is impossible to quantify. This applies to new and existing projects.

Promi-Mex | Company Report | 10

Promi-Mex: Representative Sampling Systems Equal Productivity Correctly placing sampling systems makes all the difference in determining ore grade. The right location for a sampling system depends on the characteristics of each process, as well as what results are expected from the sample. Generally, to determine the entrance mineral grade (or the mine grade) at concentrator plants, the sampling system is located after the grinding process and before the cyclone batteries. This has important advantages, but mainly that the particle size is 80 percent under 150µm. The material to be processed here is pulp, with solid percentages between 25 and 35 percent and densities of +/-1.3.

Another advantage of placing the sampling system in the right location is that less equipment is required when compared to a system installed upstream, prior to grinding. This is possible as long as there are no process changes in the grinding, such as the addition of reagents that modify the conditions of the minerals.

If these changes occur, the installation should be evaluated in the stages prior to grinding. The installation of a pre-grinding sampling system also has some restrictions and the viability of developing a project in that area will depend on the particle size.

A fundamental and recommended application is when an operation does not have its own mine or the ore it extracts is not sufficient to meet the demands of its clients. In such cases, the operation is forced to acquire ore from third parties. Just like any other product that is commercialized, the value will depend on the quality. For that reason, it is necessary to know the grade. For the most part, there are several suppliers that provide ore to the same company and the need to quantify the quality of the ore from each will result in clear conditions for both parties.

It is also critical to control the product. In many operations, each stage of the sampling process is carried out under strict, automated management to avoid human intervention, leaving out the possibility of sample contamination and fraud, which has occurred to the benefit of some of the parties.

A sampling system for particulate material, like any other type of sampler, is subject to a series of regulatory requirements so that the sample can meet its main objective: to be representative and manageable for the operator. It is also important that, depending on the process, the sample be divided into two different lines to obtain a chemical sample and a particle sample. A sampling system for this application usually has a straight path cutter, which is located at the discharge of a conveyor belt to obtain the increments from the main flow. Each of these increments is discharged to a conveyor belt that is part of the sampling system and doses the material to the secondary straight path cutter that divides the sample into chemical and granulometric lines.

In the case of the chemical line, a reduction in the size of the ore is realized by installing one or two crushing stages (crushers) to better control sampling errors. The rejects produced by the system Read the complete article More about this topic

must be returned to the downstream process and according to the configuration, they can be handled by gravity, conveyor belts or elevators.

Promi-Mex | Company Report | 11

Promi-Mex’s Experience in Chile: Mineral Sampling Towers Companies in the mining industry for the most part process material extracted from their own properties, and there are other companies that in addition to processing their own ore, acquire it from third parties. And then, there are also other companies that only buy minerals to process them in their mills.

In Chile there is an interesting case of a state company that supports small and medium producers. It provides purchasing, processing and marketing services so that they can access the metals market. The company has around fifteen “Purchasing Powers” in different regions across the country.

In addition to this company, there are other companies that are dedicated to the acquisition of minerals and due to the importance of their business, it is important to know the mineral grade of the product that the company buys and the producer sells. To determine the characteristics of the mineral, the companies have Sampling Towers, designed under strict standards to provide reliability in the measurement, both to the buyer and the seller, and to ensure that the samples obtained have the lowest possible sampling error.

The equipment that is part of the Towers must be well designed and comply with international sampling standards. In addition, sampling protocols must be carefully designed and adapted to different types of minerals, which can be by size, type, or heterogeneity. Additionally, sample collection and integrity should also be a priority when collecting minerals to avoid contamination or, in some extreme cases, fraud.

A suitable and efficient design of a Sample Tower, depending on the characteristics of the mineral, generally has a straightline primary cutter that is located at the discharge point of the conveyor belt. This is in charge of cutting off the entire flow, where the sample obtained for each increment is dosed towards a particle size reduction stage through a crusher. Once the size is reduced, the sample mass is discharged to a secondary cutter with a circular path to reduce the sample mass that will be collected at the end of the batch.

The final sample of each batch is stored in a deposit that is inside a container, to which only authorized personnel have access.

Meanwhile, products rejected from the system are returned by a conveyor belt that is part of the sampling tower.

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