Fire Assaying Reagents

B. Very strong basic flux properties

Litharge (PbO), used in fire assaying, is characterized by its:
A. Acidic flux properties
B. Very strong basic flux properties
C. Neutral flux properties
D. Amphoteric flux properties

B. Yellow to orange

The typical color of litharge (PbO) is:
A. Green to blue
B. Yellow to orange
C. White to gray
D. Red to purple

C. 883°C

The melting point of litharge is approximately:
A. 450°C
B. 660°C
C. 883°C
D. 1200°C

B. Furnishes the lead that collects Au and Ag when reduced

In fire assaying, litharge plays a key role because it:
A. Acts only as a reducing agent
B. Furnishes the lead that collects Au and Ag when reduced
C. Replaces silica in acidic slags
D. Provides carbon to aid combustion

A. Oxidizing and desulfurizing agent

Litharge acts as which type of agent during fire assay?
A. Oxidizing and desulfurizing agent
B. Reducing and carburizing agent
C. Neutralizing agent
D. Fluxing and polymerizing agent

B. The quantity of the remaining silica

The amount of litharge required in a fusion depends primarily on:
A. The carbon content of the sample
B. The quantity of the remaining silica
C. The type of collector metal used
D. The moisture content of the ore

C. Doubled

If an ore is high in alumina, the amount of litharge used should be:
A. Reduced by half
B. Equal to the copper content
C. Doubled
D. Unchanged

C. Three times the amount of copper

When the ore is high in copper, the litharge requirement is:
A. Equal to the copper content
B. Twice the copper content
C. Three times the amount of copper
D. Independent of copper content

B. Powerful basic flux

Sodium carbonate (Na₂CO₃), used in fire assaying, functions primarily as:
A. Acidic flux
B. Powerful basic flux
C. Neutral flux
D. Reducing agent

C. 852°C

The melting point of sodium carbonate is approximately:
A. 450°C
B. 660°C
C. 852°C
D. 1200°C

B. Fusible silicates and aluminates (slag)

In fire assaying, sodium carbonate combines with silica and alumina to form:
A. Metallic lead
B. Fusible silicates and aluminates (slag)
C. Ferric oxides
D. Neutral salts

B. Alternative basic flux to sodium carbonate

Potassium carbonate (K₂CO₃) in fire assaying is used primarily as:
A. Acidic flux
B. Alternative basic flux to sodium carbonate
C. Neutral flux
D. Oxidizing agent

C. Very expensive cost

Although potassium carbonate can replace sodium carbonate in fire assay, its drawback is:
A. Low reactivity
B. Very high melting point
C. Very expensive cost
D. Inability to combine with silica

B. Acid flux

In fire assaying, borax glass (Na₂B₄O₇) is primarily used as:
A. Basic flux
B. Acid flux
C. Neutral flux
D. Reducing agent

B. 742°C

The melting point of borax glass is approximately:
A. 450°C
B. 742°C
C. 883°C
D. 1200°C

B. It acts as an excellent solvent for metallic oxides

Which property makes borax glass valuable in fire assaying?
A. It increases the slag temperature
B. It acts as an excellent solvent for metallic oxides
C. It supplies lead for gold and silver collection
D. It acts as a strong reducing agent

B. Prevent the loss of ore from escaping gases

Borax glass is often used as a cover in crucibles during fire assay to:
A. Supply oxygen for combustion
B. Prevent the loss of ore from escaping gases
C. Increase the melting point of slag
D. Neutralize acidic impurities

A. Acid flux

In fire assaying, silica (SiO₂) functions mainly as:
A. Acid flux
B. Basic flux
C. Reducing agent
D. Collector of precious metals

C. 1755°C

The melting point of silica is approximately:
A. 883°C
B. 742°C
C. 1755°C
D. 852°C

D. Slag

Silica combines with metal oxides in a charge primarily to form:
A. Alloy
B. Dore bead
C. Matte
D. Slag
Answer: D. Slag

A. More fusible than silica

The slag formed by the reaction of silica with metal oxides is usually:
A. More fusible than silica
B. Non-fusible
C. Same fusibility as silica
D. Less fusible than silica

C. Reducing agent

Flour in fire assaying is classified as a:
A. Acid flux
B. Oxidizing agent
C. Reducing agent
D. Basic flux

D. Reduce PbO to metallic Pb

The main role of flour in fire assaying is to:
A. Collect gold and silver directly
B. Provide oxygen for oxidation
C. Form slag with alumina
D. Reduce PbO to metallic Pb

B. More flour is added

If the ore charge contains ferric oxide (Fe₂O₃) and MnO, then:
A. Less flour is added
B. More flour is added
C. No flour is needed
D. Flour is replaced by borax glass

D. Collect Au and Ag

The reduced metallic Pb formed from litharge by flour serves to:
A. Oxidize sulfur
B. Neutralize alumina
C. Flux silica
D. Collect Au and Ag

C. Oxidizing agent

Potassium nitrate in fire assaying primarily acts as a:
A. Reducing agent
B. Acid flux
C. Oxidizing agent
D. Collector of Au and Ag

A. 339°C

The approximate melting point of potassium nitrate is:
A. 339°C
B. 742°C
C. 883°C
D. 1755°C

B. Sulfides, arsenides, and antimonides

One of the major roles of niter in assaying is to oxidize:
A. Carbonates and silicates
B. Sulfides, arsenides, and antimonides
C. Precious metals
D. Alumina

C. Control the size of the Pb button when reducing conditions are too strong

Potassium nitrate is often added to a charge in order to:
A. Increase the size of the Pb button
B. Collect gold and silver
C. Control the size of the Pb button when reducing conditions are too strong
D. Replace borax as a flux

A. Crude bitartrate of potassium

Argols is chemically classified as a:
A. Crude bitartrate of potassium
B. Crude carbonate of sodium
C. Crude borate of calcium
D. Crude silicate of iron

B. Basic flux and reducing agent

The main role of argols in fire assaying is:
A. Oxidizing agent
B. Basic flux and reducing agent
C. Acid flux only
D. Collector of Au and Ag

C. One of the best reducing agents

Among common reagents in fire assaying, argols is regarded as:
A. Weakest reducing agent
B. Moderate oxidizer
C. One of the best reducing agents
D. Neutral flux

B. Wine barrels

Argols is traditionally obtained from:
A. Residues of iron smelting
B. Wine barrels
C. Borax deposits
D. Lead ores

B. Reducing agent in copper assay

In fire assaying, cream of tartar is mainly used as:
A. Collector of Au and Ag
B. Reducing agent in copper assay
C. Oxidizing agent for sulfides
D. Acid flux for silica

A. Refined bitartrate of potassium

Cream of tartar is chemically classified as a:
A. Refined bitartrate of potassium
B. Crude carbonate of sodium
C. Borate compound
D. Silicate mineral

B. K₂O

On heating, cream of tartar reacts to produce:
A. PbO
B. K₂O
C. Na₂CO₃
D. SiO₂

C. Argols

Cream of tartar is most closely related to:
A. Borax glass
B. Silica
C. Argols
D. Litharge

B. Strong reducing and desulfurizing agent

In fire assaying, potassium cyanide is a:
A. Strong oxidizing agent
B. Strong reducing and desulfurizing agent
C. Neutral flux
D. Acid flux

B. Potassium cyanate

When KCN reacts with oxygen, it forms:
A. Potassium sulfate
B. Potassium cyanate
C. Potassium nitrate
D. Potassium carbonate

C. Sulphocyanides

When potassium cyanide combines with sulfur, it forms:
A. Sulfates
B. Sulfides
C. Sulphocyanides
D. Silicates

A. Gold cyanidation process

One important application of KCN in metallurgy aside from fluxing is:
A. Gold cyanidation process
B. Silica removal
C. Alumina precipitation
D. Electrorefining of copper

A. Desulfurizing and reducing agent

In fire assaying, the primary role of iron is as a:
A. Desulfurizing and reducing agent
B. Acid flux
C. Powerful oxidizing agent
D. Collector of noble metals

C. More or less pure metal + iron sulfides

When iron is heated with sulfides of lead, silver, mercury, bismuth, and antimony, the reaction yields:
A. Iron nitrates
B. Iron silicates
C. More or less pure metal + iron sulfides
D. Carbonates

D. Oxide of iron (acting as a basic flux)

When iron combines with litharge, it produces:
A. Metallic lead
B. Silica glass
C. Potassium ferrocyanide
D. Oxide of iron (acting as a basic flux)

D. Spikes, nails, or an iron crucible

In assaying practice, iron is commonly used in the form of:
A. Iron sulfates dissolved in solution
B. Pure hematite powder
C. Iron filings mixed with borax
D. Spikes, nails, or an iron crucible

B. 1361 °C

What is the melting point of Fluorspar (CaF₂) in fire assaying?
A. 742 °C
B. 1361 °C
C. 883 °C
D. 1000 °C

B. Its melting point is much higher than the fusion temperature of the charge

Why is the use of Fluorspar sometimes questioned in fire assaying?
A. It easily oxidizes sulfides
B. Its melting point is much higher than the fusion temperature of the charge
C. It forms insoluble silicates
D. It collects Au and Ag when reduced

B. It becomes very fluid and helps liquefy the charge

What is the behavior of Fluorspar when melted during fire assaying?
A. It reduces PbO to Pb
B. It becomes very fluid and helps liquefy the charge
C. It reacts with silica to form silicates
D. It acts as a collector for noble metals

C. Inert; does not chemically combine with other constituents

Which statement best describes Fluorspar’s chemical reactivity in the assay charge?
A. Strong acid flux that forms aluminates
B. Powerful oxidizing agent for sulfides
C. Inert; does not chemically combine with other constituents
D. Acts as a reducing agent for ferric oxide

A. It acts as a powerful flux that dissolves alumina

What is the primary role of Cryolite in metallurgy and assaying?
A. It acts as a powerful flux that dissolves alumina
B. It reduces PbO to Pb for collection of Au and Ag
C. It prevents gas escape during fusion
D. It oxidizes sulfides and arsenides

B. Manufacture of enamels and melting of bullion

In which industrial application is Cryolite most commonly used?
A. Production of potassium cyanide
B. Manufacture of enamels and melting of bullion
C. Refining of argentiferous lead
D. As an alternative to sodium carbonate flux

B. Increases its coefficient of expansion

What effect does Cryolite have on the slag during assaying?
A. Lowers its melting temperature
B. Increases its coefficient of expansion
C. Decreases its fluidity
D. Acts as a desulfurizer

B. Its ability to dissolve alumina effectively

Which property makes Cryolite particularly valuable in aluminum metallurgy?
A. Its ability to collect noble metals
B. Its ability to dissolve alumina effectively
C. Its oxidizing power on sulfides
D. Its high melting point stability