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2026 Statistics
Key Facts: MELE Exam
3
Board Subjects
PRC Board of Metallurgical Engineering
75%
Passing Average
PRC
50%
Minimum Per Subject
PRC
3 days
Exam Duration
PRC
₱900.00
Core Exam Fee
PRC Schedule of Fees
RA 10688
Governing Law
Metallurgical Engineering Act of 2015
The MELE is a three-day objective board exam administered by the PRC Board of Metallurgical Engineering under RA 10688. It covers three subjects: Metallurgy I (35%), Metallurgy II (35%), and Metallurgy III (30%). Passing requires a weighted general average of at least 75% with no rating below 50% in any subject. The exam covers extractive metallurgy, physical and mechanical metallurgy, mineral processing, and engineering economics and laws.
Sample MELE Practice Questions
Try these sample questions to test your MELE exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1In froth flotation, what is the primary role of a 'collector' reagent such as Potassium Amyl Xanthate (PAX)?
A.To selectively adsorb onto the target mineral surfaces and render them hydrophobic
B.To stabilize the air bubbles and form a stable froth at the top of the cell
C.To deactivate the surface of unwanted minerals to prevent them from floating
D.To alter the pH of the slurry to ensure optimal chemical activity of other reagents
Explanation: Collectors are heteropolar organic compounds that selectively adsorb onto specific mineral surfaces. They orient their polar groups toward the mineral and non-polar hydrocarbon chains outward, rendering the mineral surface hydrophobic (water-repellent) so it can attach to air bubbles and float.
2According to Bond's Law of Comminution (Work Index), the energy required to crush or grind ore is proportional to what parameter?
A.The difference between the square roots of the feed size and product size
B.The difference between the reciprocals of the square roots of the product size and feed size
C.The logarithm of the ratio of feed size to product size
D.The difference between the surface areas of the feed and product particles
Explanation: Bond's Third Theory of Comminution states that the work input (W) is proportional to the difference between the reciprocals of the square roots of the product size ($P_{80}$) and feed size ($F_{80}$), expressed as $W = 10 \cdot W_i \cdot (1/\sqrt{P_{80}} - 1/\sqrt{F_{80}})$, where $W_i$ is Bond's Work Index.
3In mineral processing, what is the operating principle of a Wilfley table?
A.Separating particles based on differences in density using a reciprocating deck and film flow
B.Separating particles by magnetic susceptibility using high-intensity magnets
C.Classifying particles by size using centrifugal force in a wet cyclone
D.Concentrating minerals by differences in surface chemistry using air bubbles
Explanation: The Wilfley table is a shaking table that separates minerals of different densities. It uses a thin film of water flowing down a tilted deck, combined with a reciprocating motion along the deck's length, causing heavy mineral particles to travel along the riffles while lighter waste particles are washed over the riffles.
4Which of the following minerals is considered strongly ferromagnetic and is typically separated using low-intensity magnetic separators (LIMS)?
A.Magnetite
B.Hematite
C.Chalcopyrite
D.Quartz
Explanation: Magnetite ($Fe_3O_4$) is a ferromagnetic mineral with high magnetic susceptibility, which allows it to be easily captured and separated from non-magnetic gangue using low-intensity magnetic separators (LIMS).
5What is the stoichiometric chemical equation that represents the cyanidation of gold, commonly known as Elsner's Equation?
A.4Au + 8NaCN + O2 + 2H2O -> 4Na[Au(CN)2] + 4NaOH
B.2Au + 4NaCN + H2O -> 2Na[Au(CN)2] + NaOH + H2
C.Au + 2NaCN + H2O -> Na[Au(CN)2] + NaOH + 0.5H2
D.4Au + 8NaCN + 2H2O -> 4Na[Au(CN)2] + 4NaOH + H2
Explanation: Elsner's Equation represents the dissolution of gold in an alkaline cyanide solution in the presence of oxygen: $4\text{Au} + 8\text{NaCN} + \text{O}_2 + 2\text{H}_2\text{O} \rightarrow 4\text{Na}[\text{Au}(\text{CN})_2] + 4\text{NaOH}$. Oxygen is critical as the oxidizing agent in this reaction.
6How is an Ellingham diagram utilized in pyrometallurgy?
A.To determine the thermodynamic feasibility of reducing a metal oxide with carbon or carbon monoxide at various temperatures
B.To calculate the rate of reduction reactions of oxides in a blast furnace
C.To map out the phase transitions and solid solubility of carbon in iron alloys
D.To evaluate the viscosity and basicity of metallurgical slag compositions
Explanation: An Ellingham diagram plots the standard Gibbs free energy of formation of oxides (or sulfides) against temperature. It allows metallurgists to compare the relative stability of oxides and determine at what temperatures carbon, carbon monoxide, or other metals can reduce a given metal oxide.
7What is the primary thermodynamic objective of roasting sulfide ores prior to smelting?
A.To convert metal sulfides into oxides or sulfates, which are much easier to reduce to metallic form
B.To melt the ore completely so that the slag can separate from the matte
C.To lower the melting point of the copper concentrates by adding silica flux
D.To vaporize the metallic copper directly from the sulfide minerals
Explanation: Roasting is a solid-gas reaction conducted below the melting point of the charge. Its goal is to oxidize metal sulfides (e.g., $CuFeS_2, FeS_2$) to oxides (e.g., $CuO, Fe_2O_3$) or sulfates, releasing sulfur dioxide gas. Metal oxides are much more easily reduced to metals using carbonaceous agents than sulfides.
8In copper pyrometallurgy, what is 'copper matte'?
A.A molten solution of copper sulfide (Cu2S) and iron sulfide (FeS) obtained after smelting
B.A waste product consisting of silicates and oxides of iron and calcium
C.Pure blister copper containing dissolved sulfur dioxide gas bubbles
D.A solid residue of copper and zinc oxides ready for leaching
Explanation: Copper matte is the intermediate liquid phase produced in copper smelting furnaces. It is a mutually soluble mixture of copper(I) sulfide ($Cu_2S$) and iron(II) sulfide ($FeS$), which has a higher density than the silicate slag, allowing it to settle at the bottom of the furnace.
9How is the basicity index (B) of a metallurgical slag typically calculated in steelmaking?
A.By dividing the weight percent of basic oxides (like CaO and MgO) by the weight percent of acidic oxides (like SiO2 and Al2O3)
B.By measuring the hydrogen ion concentration (pH) of the molten slag using electrochemical probes
C.By dividing the weight of silica flux by the total weight of calcium carbonate added
D.By measuring the viscosity of the slag and taking the reciprocal value
Explanation: The basicity of slag is chemically defined by the ratio of basic components (network modifiers like $CaO, MgO$) to acidic components (network formers like $SiO_2$). The simplest expression is $B = \%\text{CaO}/\%\text{SiO}_2$, or more comprehensively $B = (\%\text{CaO} + \%\text{MgO})/(\%\text{SiO}_2 + \%\text{Al}_2\text{O}_3)$.
10Which of the following refractory materials is classified as basic and is commonly used in basic oxygen steelmaking (BOF) linings?
A.Magnesite (MgO)
B.Silica (SiO2)
C.Fireclay (Al2O3-SiO2)
D.Silicon Carbide (SiC)
Explanation: Magnesite ($MgO$, often as magnesia-carbon bricks) is a basic refractory material. It is chemically compatible with the basic slags ($CaO$-rich) used in steelmaking to remove phosphorus and sulfur, preventing rapid chemical dissolution of the furnace lining.
About the MELE Practice Questions
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