Lead or Tin Chloride, white powder? Or silver

[oldtimmer]

I have just finshed proccessing a fouth batch of computer pins. I can not do them in the gold cell as they are too small and fall through the copper screen.

I have had them cooking in HCl for the last three days. I will pour off the liquid as it becomes full of iron(?). The color of the HCL after boiling for a while was a brownish color (irin chloride?). So today as I was filtering the gold from the solution and when I went to clean the filter and the gold, the spent acid turned cloudy and then formed a white precepitate when I went to wash the gold. I use water from my house RO system that has a deionizer after the filter. The steel from the pins have been been disolved and only the gold is left. The HCL/Iron Chioride has been poured off three or four times and fresh HCL added each time. There was a small amout of solder in the pins when I started, but should have mostly been eliminated along with the spent acid. As a side note, when I tested the pins to start, they were only slightly magnetic when checked with a maginet. They were attracted, but did not want to stay on the maginet.

I initially thought that it might be silver, but do not believe that silver will disolve directly in HCl, even when it is hot. The filter paper initially turned a greyish black color in the sun, then turned into a dirty lime greenish color. I put a little fresh HCl in the solution and heated it some and all of the white precepitate redisolved, so that it si not a problem with the gold foils.

Question is, what is the white precepitate? I am puzzled at a loss due to the color change of the filter paper when allowed to dry in the sun.

 

[lazersteve]

Say hello to Copper I Chloride. You will come to know it very well (I hope you learn to recognize it anyway...).

I have preached on this one until I'm blue in the face. :mrgreen:

The pins were slightly magnetic due to the nickel undercoat on the plating.

All of your descriptions are classic copper I chloride reactions : insoluble in water, dark brown in solution, dissolves in HCl, and lime green when dry. The only other common form you did not mention was the light tan or dark gray crystalline form (like table salt). This is usually found in the bottom of the reaction vessel along with your foils.

Anytime you dissolve copper into a chloride solution until it is saturated you will get this as a by product.

Steve

 

[oldtimmer]

Steve,

Thanks for the fast reply. I had not thought about Coper 1 Chloride as the HCl never turned the typically greenish, but a light blueish. I will but this in the memory banks for future use.