Aluminum electrolysis production knowledge test paper

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I. Multiple-choice questions (1 point for each question, 20 points in total) 1. Aluminum is a type of (A) metal. A. Light metals B. Heavy metals C. Rare metals D. Precious metals 2. In the electrolytic production of aluminum, the main component of the electrolyte is (A), and its chemical formula is (E). A. Cryolite B. Aluminum fluoride C. Sodium fluoride D. AlF3 E. Na3AlF6 F. NaF 3. An electrolyzer cell series is composed of many electrolyzer cells (A) connected together; it represents the basic unit in aluminum production. For a single electrolyzer series, there are two ways in which the electrolyzers can be arranged: (D) and (E). A. Series B. Parallel C. Hybrid D. Vertical E. Horizontal 4. Direct current flows from the positive pole of the rectifier, through the trench busbar, the column busbar, and the anode main busbar, before entering the (B) of the first slot; it then passes through (C) and reaches the cathode carbon blocks via (A). A. Molten aluminum B. Anode C. Electrolyte D. Cathode busbar 5. During the operation of removing the anode, there is a procedure involving “three touches and one push”; the “three touches” refer to (ABC). A. Checking the condition of the furnace bottom B. Checking the condition of the adjacent remaining anode C. Checking the condition of the furnace walls on the sides D. Checking the temperature of the anode clamps 6. The precision requirement for aluminum absorption is that it should not exceed (B), and it must be at least 10 Kg. A. 15–25 Kg B. 25–50 Kg C. 35–50 Kg D. 15–35 Kg 7. An electrolyte formed from cryolite with a molar ratio greater than 3 is called (B); in industry, (A) is used for its production. A. Acidic electrolyte B. Basic electrolyte C. Neutral electrolyte D. Positive cryolite 8. The theory that suggests the occurrence of the anode effect is due to changes in the charge carried by bubbles is (C) A. Wetting theory B. Fluoride ion discharge theory C. Electrostatic attraction theory D. Comprehensive theory 9. The option that represents the operation of replacing the anode is (D) A. NB B. RR C. RC D. AC 10. When baking coke particles, (A) is used to create parallel current paths in order to gradually increase the current in the input tank. A. Shunt B. Flexible busbar C. Lifting frame D. Thermocouple 11. The voltage allocated to various effects in an aluminum electrolysis cell, VACT, includes the following items (AB): A. VNET B. VAE C. VNOM D. Average voltage. II. Fill-in-the-blank questions (2 points per blank, 40 points in total) 1. During the aluminum electrolysis process, the reactions that occur at the anode are O2—2e=O, 2O+C=CO2, while the reactions that occur at the cathode are Al3++3e=Al. 2. The main raw material used in aluminum electrolysis production is alumina, with the molecular formula Al2O3. 3. Aluminum electrolyzers can be divided into two main categories based on the type of anode structure: self-baking anode electrolyzers and pre-baked anode electrolyzers. 4. Industrial electrolyzers typically consist of four main parts: the cathode structure, the upper structure, the busbar structure, and electrical insulation. 5. There are four common methods for preheating and baking aluminum electrolysis cells: the molten aluminum preheating method, the coke particle baking method, the graphite powder baking method, and the fuel preheating method. 6. The cycle for replacing the anode is determined by the anode height and the anode consumption rate. 7. The quality control points for aluminum output are the connection to the computer and the accuracy of aluminum absorption. 8. The methods for measuring aluminum levels and electrolyte levels typically include the three-point measurement method and the one-point measurement method. 9. The main factors affecting changes in electrolysis temperature include current intensity, cell voltage, water levels, and the anode effect coefficient, among others. 10. Fluctuations in the aluminum melt within the tank, caused by certain factors, lead to changes in the pole distance, which in turn results in voltage fluctuations; this phenomenon is known as voltage swing/pin wobble. III. True or False Questions (1 point per question, 10 points in total) 1. The physical meanings of the initial crystallization temperature and the melting point are the same. (×) 2. As the molar ratio of the electrolyte decreases, its initial crystallization temperature also decreases. ( √ ) 3. During the start-up process of baking the electrolyzer, the pouring of aluminum indicates that the electrolyzer has entered the production phase. (√ ) 4. If the anode current density is high and the current efficiency is good, the replacement cycle for the anode will also be shortened. (√ ) 5. When installing a new anode, its base should be positioned at the same level as that of the old anode. (× ) 6. If an anode effect occurs during aluminum extraction, extraction should be stopped immediately; operations should resume only after the effect subsides. (√ ) 7. When an anode effect occurs, it should be extinguished as soon as possible. (× ) 8. Operating the electrolyzer by applying electricity means creating a short circuit between certain points. (× ) 9. An excessive amount of aluminum melt in the electrolyzer can cause the temperature inside the electrolyzer to drop. (√ ) 10. The net voltage of an electrolyzer is the cell voltage, excluding the voltage associated with any effects. (√ )

IV. Term Explanations (3 points per question, total 9 points)
1. Pole distance: The distance between the base of the anode and the surface of the aluminum melt at the cathode.
2. Mole ratio: The ratio of the number of moles of sodium fluoride to the number of moles of aluminum fluoride in cryolite is known as the mole ratio of cryolite.
3. Electrical energy efficiency: The ratio of the energy theoretically required to produce a certain amount of aluminum metal to the actual energy consumed.

V. Short Answer Questions (7 points per question, total 21 points)
1. Briefly describe the steps involved in replacing an anode. 1. Remove the trough cover, 2. Remove the material, 3. Connect to the computer, 4. Create a gap, 5. Release the clamps, 6. Lift out the anode, 7. Mark lines, 8. Retrieve the pieces, 9. Position the new anode, 10. Set up the new anode, 11. Finish trimming, 12. Add insulation material, 13. Complete the process. 2. Briefly describe the steps for measuring two levels. (1) Operate the aluminum outlet hammer to open the cover of the aluminum outlet, exposing the electrolyte. (2) Insert a 135° measuring rod into the aluminum outlet; place a level on top of it and maintain this position for 10 seconds. (3) Quickly remove the measuring rod and place it horizontally on the ground; using the dividing line, determine the two horizontal levels. (4) Record the data, remove the adhesive layer from the measuring rod, and proceed to measure the next cell. 3. List the main reasons for the decrease in the current efficiency of the electrolytic cell. (2) Dissolution and re-oxidation loss of aluminum (3) Incomplete discharge of higher-valent aluminum ions