How Much Power Is Needed to Melt Lead?

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Discussion Overview

The discussion revolves around calculating the power required to melt lead, focusing on theoretical approaches rather than practical applications. Participants explore various methods of heating, including electrical arcs and induction melting, while considering the specific heat and latent heat of fusion for lead.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire about the theoretical calculations needed to determine the watts required to heat lead to its melting point, specifically mentioning the use of specific heat and latent heat of fusion.
  • Others suggest that the method of heating (e.g., electrical arc versus induction furnace) significantly influences the calculations and efficiency.
  • A participant notes that the question is more related to thermodynamics than electronics, emphasizing that the wattage affects the speed of heating rather than the maximum temperature achievable.
  • Some participants express concerns about the safety and practicality of arc melting lead, while others clarify that the discussion is purely theoretical and not intended for real-world application.
  • One participant proposes a series of calculations involving energy, arc distance, and joule heating to estimate the power needed to melt the lead cube.
  • Another participant mentions the importance of considering heat loss and insulation when calculating the necessary power, suggesting that efficiency plays a critical role in the overall process.
  • References to external sources, such as articles on electric arc furnaces and efficiency studies, are provided to support claims about energy requirements and melting processes.

Areas of Agreement / Disagreement

Participants generally agree on the theoretical nature of the question and the need for calculations involving specific heat and latent heat. However, there are multiple competing views regarding the best method to approach the problem, the significance of safety concerns, and the role of thermodynamics versus electronics in the discussion.

Contextual Notes

Participants note limitations in their ability to conduct real experiments and express uncertainty about the efficiency of different heating methods. The discussion also highlights the need for clear definitions and specifications regarding the type and amount of metal involved in the calculations.

Who May Find This Useful

This discussion may be useful for individuals interested in theoretical physics, thermodynamics, and electrical engineering, particularly those exploring the heating and melting processes of metals.

JoeSalerno
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This question is purely theoretical, so don't worry about safety or doability. Is there a way of calculating how many watts it takes to heat different metals? To be specific, how many amps and bolts it would take to get lead to its melting point. Thanks in advance.
 
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berkeman said:
Sounds like you are asking about Induction Furnaces and Induction Melting:

https://en.wikipedia.org/wiki/Induction_furnace

What type of metal, and how thick?
It actually sounds pretty similar to an induction furnace, but this would be without direct contact. It would be from an electrical arc. For simplicity, the material would be about a .75 cm cube of lead.
 
Lead melts in the same way as ice . So you need to use specific heat and then latent heat of fusion to find out how much heat is actually needed to melt the cube

Factor in then the efficiency of the heating process .

I know that this is a theoretical question but please note anyway that arc melting of lead is not recommended for a whole raft of practical and safety reasons .

Lead is usually just melted in a flame heated crucible .

Small amounts can be melted with a soldering iron for that matter .
 
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Nidum said:
Lead melts in the same way as ice . So you need to use specific heat and then latent heat of fusion to find out how much heat is actually needed to melt the cube

Factor in then the efficiency of the heating process .

I know that this is a theoretical question but please note anyway that arc melting of lead is not recommended for a whole raft of practical and safety reasons .

Lead is usually just melted in a flame heated crucible .

Small amounts can be melted with a soldering iron for that matter .
So, I found the specific heat (0.128 J/kg Kelvin) and the latent heat (23 kJ/kg). How would I find a value for the efficiency?
 
You'll probably need to do some experiments .

Exactly how is the block to be heated ?
 
Nidum said:
You'll probably need to do some experiments .

Exactly how is the block to be heated ?
I was afraid somebody might say that. The cube of lead would be heated via an electrical arc.
 
JoeSalerno said:
The cube of lead would be heated via an electrical arc.
Nidum said:
please note anyway that arc melting of lead is not recommended for a whole raft of practical and safety reasons .
Do you understand the safety issues that Nidum points out?
 
Nidum said:
You'll probably need to do some experiments .

Exactly how is the block to be heated ?
I've thought of some calculations I could use, if I find the formulas.
1. If I use specific heat as well as latent heat of fusion in the correct formula, I believe that tells me how much energy the system needs.
2. I'd calculate the distance of an electrical arc and the wattage that comes through to the other end.
3. Some sort of formula for knowing how to calculate the watts needed to heat a metal using joule heating.

This would tell me how much power I need to melt the lead, of which I can determine what arc distance and for how long the energy has to flow. If that made any sense, does that sound right?
 
  • #10
berkeman said:
Do you understand the safety issues that Nidum points out?
Yeah, I figured this was pretty dangerous, that's why I want to avoid doing real experiments. In the beginning of the thread I stated that I was going to disregard any feaseability or safety issues because this is purely theoretical. I don't plan on doing any of this irl.
 
  • #11
The question is more related to thermodinamics than electronics. The 'watt' is just the speed of providing energy (by electronics means): the temperature it can reach purely depends on the heat loss/insulation.
The 'watt' value also has effect on the speed of the heating, but then that's all.
 
  • #12
Rive said:
The question is more related to thermodinamics than electronics. The 'watt' is just the speed of providing energy (by electronics means): the temperature it can reach purely depends on the heat loss/insulation.
The 'watt' value also has effect on the speed of the heating, but then that's all.
Is there really a way to solve this problem without doing real testing? If not, is there at least a dumbed down, high school electronics level way of solving this? If neither of those are an option, I don't have the money, materials, or the level of ignorance to test this for real.
 
  • #13
JoeSalerno said:
... is there at least a dumbed down, high school electronics level way of solving this?
You have to rebuild the question first.

Specify the amount and the type of metal you want to use and ask the amount of necessary heat somewhere in the 'general physics' part (of course there are people here too who can solve this, but: even so, it's definitely not electronics).

Then you can ask here that what kind of heating can provide that heat, at what power, in what time? That part will be electronics (more or less).

As the question is now, it's quite hard to 'solve'. Now it is a bit like 'The Almighty Answer to the Meaning of Life, the Universe, and Everything'.
 
  • #14
In #9 point 1 gives you the energy needed to melt the lead. Then if you were to assume no heat losses the power required depends on how fast you want to melt it. Power=energy/time. If the heat losses were say 50% then it would take roughly twice as long or you need twice the power.Try searching for papers on the efficiency of arc smelting? I don't have access but perhaps something like this one would have data

https://link.springer.com/article/10.1134/S0036029510120141
 

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