Obtaining a Fluid for Primary Batteries and Utilizing the Waste Products of such Batteries.
Year: 1891

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by JOSEPH BROWN GARDINER, of Nyack, in the
County of Rockland and State of New York, one of the United States of
America, Electrician.]
'
Obtaining a Fluid for Primary Batteries and Utilizing the Waste
Products of such Batteries.
I, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E., Fel. Ch. Inst. P.A.,
(practising as Phillips & Leigh,) of No. 22 Southampton Buildings, Chancery
Lane, in the County of Middlesex, Engineer and Patent Agent, do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement :-
My invention relates to primary batteries, and more accurately speaking to a
method or process whereby I am enabled to obtain, at one point thereof, an
efficient and comparatively cheap fluid for employment in the battery, and there-
after, in the further employment of my method or process, to recover the original
substances employed in the process, together with the metal or the oxide of the
metal which constitutes the electrode acted upon by the battery fluid.
It has been known for many years to electricians and to others skilled in the art,
that the large cost of employing primary batteries is mainly due to the waste of
zinc or other metal employed, and accordingly many efforts have been made to
diminish, as far as is possible, the waste of metal, and to recover it in such form
that it may be re-utilized or sold, as desired. These ends I have secured in the
employment of my method, and this feature 1 regard as one of the principal
advantages I secure. Another important point gained is the obtaining of an
electrolytic fluid possessing all the requirements of a high-grade electrolyte. Other
and further advantages arising under my method or process will appear in the
detailed description thereof presently to be set forth.
I desire it to be understood that I regard as comprised within the spirit of my
invention, and as fully embraced herein, the broad method or process, and the
various specific methods or processes which may fairly arise from the practice of
the general method, and which are set forth in detail at the end of this Specification
in the claims.
First in order, I will indicate briefly the scope and extent of my general method,
and leave the description of the more specific parts to be gathered from the detailed
account that follows. My general method, then, comprises these steps:
1. Separating a salt containing the depolarizing element into two parts, which I
will designate for convenience as Part A and Part B.
2. Using part A, which contains the depolarizing element, singly, or in connection
with other substances in the battery fluid.
3. After Part A becomes combined with the metal, or becomes electrically
"spent," separating out the metal or its oxide.
4. Combining what is left by Step 3 with the Part B originally separated out,
thereby obtaining the salt originally employed.
It will be at once obvious that this method is equally applicable to single-fluid
and double-fluid batteries, but I intend to illustrate its application to a well-known
form of double-fluid battery as most convenient.
Further, my method may be carried out with a large variety of salts and other
elements, and I do not desire to have it thought that the scope of the general
method is limited either by the character of the materials described or by its
application to a two-fluid cell.

page_text: The two-fluid battery which I have selected to illustrate my method is, broadly
speaking, of this type: In the interior porous cup is contained an electrode of
zinc combined with mercury, either as an alloy or an amalgam, and a bath of
slightly acidulated water. In the exterior or-containing cup is the carbon electrode,
and, ordinarily, a solution of bi-chromate of potash, treated with sulphuric acid.
prefer to use, however, a bath of chromic acid in place of that of bi-chromate of
potash and sulphuric acid, for the reason that the latter, upon standing, forms very
readily a double sulphate of chromium and potash, which attaches itself to the
carbon and thereby seriously impairs its electric qualities in the manner well
understood.
For this reason I prefer to employ a dilute solution of chromic acid, which, when
combined with its proper amount of dilute nitric acid, or other acid or acid salt,
keeps the electrodes free from deposition of foreign matter, and throughout enables
both the zinc and carbon to remain clean. Or still further I contemplate the
employment of chromic acid, unassisted, in the bath. However, it must be noted
that the employment of dilute nitric or other acid, or of the acid salt, not only keeps
the electrodes clean and free from deposition, but further it has the added value of
supplying oxygen in the third step of my process. This one point of advantage
in the employment of chromic acid in the bath is amply sufficient to warrant its
substitution for the bi-chromate of potash; but it is further to be noted that the
"spent
" bi-chromate of potash, because of its complex form, is practically
valueless, so far as regards the recovery of the expended zinc, or other elements.
Instead of using the commercial chromic acid (H,CrO4), which is obtained by
combining tri-oxide of chromium (CrO,) with water (H,O), I obtain it quite as
readily and cheaply from the treatment of "chrome yellow," or chromate of lead,
or other chromate or bi-chromate, with sulphuric acid. This step also enables me
to secure a residuum which is of the utmost importance to me in the final step of
the process. As an added advantage of this part of my method, I would here state
that the "spent" chromic acid, when the commercial form is employed, is not
easily susceptible to treatment for the recovery of elements. By my method,
however, am enabled to employ a high grade of chromic acid, and further on to
recover all, or almost all, of the original elements.
The reaction which constitutes Step 1 of my process is practically as follows, the
minor reactions being disregarded: Chromate of lead and sulphuric acid give me
chromic acid (Part A) and sulphate of lead (Part B).
PbCrO + H₂SO₁ + Aq= H₂CrO, + PыSO, + Aq.
The chromic acid is employed in dilute solution, either with or without an
additional acid or acid salt, in connection with the carbon electrode. Osmotic
action begins, the circuit having been closed. By ex-osmotic action, the acidulated
water with zinc flows into the outer or containing cup, and by endosmotic action the
solution of chromic acid enters the interior cup where it attacks the zinc. This
continues until the difference in electrical potential is lost, which also marks the
termination of Step 2 of my method.
The baths, either combined or singly, are treated with an alkaline carbonate, or
other alkaline salt, preferably carbonate of potash, and then evaporated.and ignited
in a reverberatory furnace in the customary manner. It will be seen that upon
ignition the carbon supplied by the carbonate. of potash is consumed, and that
chromate of potash and oxide of zinc remain. From the resulting product the
chromate of potash can be readily dissolved out, and the zinc oxide remains. This
operation constitutes Step 3 of my process.
Although I have referred in Step 3 to the employment of carbonate of potash, it
will be evident that other alkaline carbonates or alkaline salts (such as an alkaline
sulphate) might have been employed. In fact, in some instances I have found the
employment of other alkaline salts to be most advantageous.
Step 4 is then resorted to and is simple in theory and practice. The chromate
of potash is combined with the sulphate of lead, obtained in Step 1 and constituting

page_text: Part B. This gives the original salt, chromate of lead, as a precipitate, and leaves
sulphate of potash. The reaction may be generally expressed as follows:
K,CrO + PbSO₁ + Aq=PbCrO4 + K₂SO, + Aq.
To recapitulate, I will briefly state the various steps of my specific process in
the same manner as I stated the broad or general method.
1. Treating chromate of lead with sulphuric acid, and obtaining chromic acid
(Part A) and sulphate of lead (Part B).
2. Using chromic acid in dilute solution as a battery fluid, with or without the
aid of another acid or acid salt.
3. Treating "spent " chromic acid, etc., with carbonate of potash or other
alkaline salt, drying and igniting, and dissolving out the chromate of potash, leaving
zinc oxide.
4. Treating sulphate of lead (Part B) with chromate of potash, giving chromate
of lead and sulphate of potash.
As a slight variation of this specific method, it is to be noted that carbonate of
lime might have been employed in Step 3, in place of carbonate of potash, in which
case I would have obtained sulphate of lime in Step 4.
To obtain carbonate of potash from the sulphate of potash secured in Step 4, as
described, it is necessary merely to precipitate it with carbonate of lime or chalk,
which at once gives me sulphate of lime and also carbonate of potash, which latter
may be re-employed, as before noted in Step 3. It is to be observed that in either
case, whether I use carbonate of lime directly in Step 3, or carbonate of potash,
and then after Step 4 recover the carbonate of potash, I obtain finally chroniate of
lead and sulphate of lime, and that the substances which do not reappear are lime
and sulphuric acid. These combine and form sulphate of lime, an article having a
commercial value quite equal to that of the uncombined lime and sulphuric acid.
As to the zinc oxide which is recovered in Step 3, it has a high commercial
value, and the gain in weight occasioned by the combination of oxygen with the
original zine more than compensates for the slight waste involved in the various
operations. Thus it follows that the experse of the entire method or process is
limited to the slight waste in chromate of lead or "chrome yellow" involved in
the different steps, and the cost of labor and skill involved in the manipulation.
As to the waste of chromate of lead, however, I am of the opinion that it
slight, and that even this slight waste is compensated by the process of obtaining
chromic acid from chromate of lead, which is cheaper than employing the bi-oxide
of chromium directly.
I am
very
One other marked advantage in the use of my method is to be noted here.
enabled throughout to handle powders and solids, in place of acids, and it will be
readily understood that this is of vast importance both as concerns the freedom
from danger and ease in handling, and the convenience and simplicity in
transportation.
As I have before stated, a great variety of salts and other elements is possible
in the carrying out of my general method. Thus, for example, I could inaugurate
it by the treatment of bi-chromate of potash with hot sulphuric acid. This and
other variations I regard as within the spirit of my broad idea.
To still further indicate the scope of my invention, and the great variety of
methods it may comprehend, I will now refer to a modification, which I regard as
of the greatest importance. It will be noted in this modification that, because of
the character of the elements employed, the number of steps required to complete
the cycle is reduced from four to three. In this instance I inaugurate the method
with the employment of chromate or bi-chromate of lime, soda or potash, or other
alkaline salt. Treating this salt, say chromate of lime, for example, with sulphuric
acid, 1 readily obtain chromic acid and sulphate of lime. In Step 2, the chromic
acid is employed, as before, with or without another acid or acid salt in the battery
solution, In Step 3, I treat the "spent " fluid with either carbonate of lime or the

page_text: sulphate of lime produced in Step 1, or other alkaline salt, dry, and ignite, and
obtain as a result chromate of lime, with which I started, and zinc oxide.
It will be seen that I can use in Step 3 either the sulphate of lime produced in
Step 1, or, if desired, I can employ carbonate of lime and dispose of the sulphate
of lime in the market. In practice I have found the latter alternative desirable,
because of the extremely pure quality of the sulphate of lime obtained in this
process.
Although I have illustrated this modification by using chromate of lime in
Step 1, it is obvious that it might have been carried out by starting in with a salt
of soda or potash. For instance, if for any reason I inaugurate the method with
chromate of potash in Step 1, I could, if desired, still employ the carbonate of
lime in Step 3, which would leave me with chromate of line at the end of the
process. This would enable me to re-commence the method with chromate of lime,
and to sell the sulphate of potash obtained in Step 1. Or could instead employ
the sulphate of potash in Step 3, as desired.
I will summarize the points of this three-step method in the same manner as I
have previously summarized the points of the four-step method:
1. Treating an alkaline salt (e.g., chromate of lime) with an acid (e.g., sulphuric)
and obtaining a depolarizing agent (e.g., chromic acid, or Part A) and a residuum
(e.g., sulphate of lime, or Part B).
2. Using the depolarizing agent (e.g., chromic acid) in dilute solution as a
battery fluid with or without the aid of another acid or acid salt.
3. Treating the "spent" depolarizing fluid (e.g., chromic acid) with an alkaline
salt (e.g., carbonate of lime) or the residuum of Step 1 (e.g., sulphate of lime or
Part B), drying, igniting and obtaining the original alkaline salt (e.g., chromate
of lime) and the oxide of the metal of the electrode, which latter may be readily
separated out.
A's before noted, in case the new alkaline salt (or carbonate of lime in the above
example) is employed in Step 3, then the residuum of Step 1 (e.g., sulphate of
lime, or Part B) will still remain and may be disposed of in the market.
My method as set forth is simple and direct. There is practically no waste in
the chemical elements employed, and there are no difficult or inconvenient
operations in their employment.
The batteries in connection with which my method is employed are of high
voltage, small internal resistance, and large capacity, and are liable in the smallest
degree to depositions and other injurious local action. The high efficiency of these
batteries and the possibility of reclaiming all the effective material gives me a
practical solution of the problems involved in the use of primary batteries, and
enables me to reduce the expense to a minimum.
Having thus accurately described my method and indicated various ways in
which the same may be practised, I would state that what I regard as of the spirit
of my invention, and desire to secure by Letters Patent, is as follows:
1. The method comprising the following steps: Separating a salt into two
parts, one of which contains the depolarizing element; using the depolarizing
clement thus obtained in a battery fluid; treating the "spent" depolarizing
fluid so as to recover the metal consumed; and combining the remainder
of the "spent" depolarizing fluid with the unused part of the salt obtained in the
first step.
2. The method comprising the following steps: Separating a salt into two parts,
one of which contains the depolarizing element; using the depolarizing element
thus obtained alone or in combination with an acid or acid salt in a battery fluid;
treating the "spent " depolarizing fluid so as to recover the metal employed or the
oxide of that metal; and combining the remainder of the "spent" depolarizing
fluid with the unused part of the salt obtained in the first step.
3. The method comprising the following steps: Treating a salt with an acid so

page_text: "
as to separate it into two parts, one of which contains the depolarizing element;
using the depolarizing element thus obtained alone or in combination with an acid
or acid salt, in a battery fluid; treating the " *pent depolarizing fluid so as to
recover the metal employed or the oxide of that metal; and combining the remainder
of the "spent" depolarizing fluid with the unused part of the salt obtained in the
first step, to recover the original salt employed.
4. The method comprising the following steps: Treating a salt with an acid so
as to separate it into two parts, one of which contains the depolarizing element;
using the depolarizing element thus obtained alone or in combination with an acid
or acid salt in a battery fluid; treating the "spent" depolarizing fluid with an
alkali, alkaline carbonate or alkaline salt, so as to recover the metal employed, or
the oxide of that metal; and combining the remainder of the "spent" depolarizing
fluid with the unused part of the salt obtained in the first step, to recover the
original salt employed.
5. The method comprising the following steps: Treating a salt with an acid so
as to separate it into two parts, one of which contains the depolarizing element ;
using the depolarizing element thus obtained alone or in combination with an acid
or acid salt, in a battery fluid; treating the "spent" depolarizing fluid with an
alkali, alkaline carbonate or alkaline salt, drying and igniting, and treating so as to
recover the metal employed, or the oxide of that metal; and combining the remainder
of the "spent" depolarizing fluid with the unused part of the salt obtained in the
first step, to recover the original salt employed.
6. The method comprising the following steps: Treating a chromate of lead, or
other chromate, with an acid, so as to separate it into two parts, one of which
contains chromic acid; using the chromic acid thus obtained alone or in combination
with an acid or acid salt in a battery fluid; treating the "spent " chromic acid so
as to recover the metal employed, or the oxide of that metal; and combining the
remainder of the "spent" chromic acid with the unused part of the chromate of
lead or other chromate obtained in the first step, to recover the original chromate
of lead or chromate employed.
7. The method comprising the following steps: Treating a chromate of lead or
other chromate with an acid so as to separate it into two parts, one of which
contains chromic acid; using the chromic acid thus obtained alone or in combina-
tion with an acid or acid salt, in a battery fluid; treating the "spent" chromic
acid with an alkali, alkaline carbonate or alkaline salt, so as to recover the metal
employed or the oxide of that metal; and combining the remainder of the "spent
chromic acid with the unused part of the chromate of lead or other chromate
obtained in the first step to recover the original chromate of lead or chromate
employed.
"
8. The method comprising the following steps: Treating a chromate of lead or
other chromate with an acil so as to separate it into two parts, one of which
contains chromic acid; using the chromic acid thus obtained alone or in combina-
tion with an acid or acid salt in a battery fluid; treating the "spent" chromic acid
with an alkali, alkaline carbonate or alkaline salt, drying and igniting, and treating
so as to recover the metal employed or the oxide of that metal; and combining the
remainder of the "spent" chromic acid with the unused part of the chromate of
lead or other chromate obtained in the first step, to recover the original chromate
of lead or other chromate employed.
9. The method comprising the following steps: Treating a chromate of lead or
other chromate with sulphuric acid, so as to separate it into two parts, one of which
contains chromic acid and the other sulphate of lead or other sulphate; using the
chromic acid thus obtained alone or in combination with an acid or acid salt, in a
battery fluid; treating the "spent" chromic acid so as to recover the metal
employed or the oxide of that metal; and combining the remainder of the "spent
chromic acid with the sulphate of lead or other sulphate obtained in the first step,
in order to recover the original chromate of lead or other chromate employed.
"
10. The method comprising the following steps: Treating a chromate of lead or

page_text: other chromate with sulphuric acid, so as to separate it into two parts, one of which
contains chromic acid, and the other sulphate of lead or other sulphate; using the
chromic acid thus obtained alone or in combination with an acid or acid salt, in a
battery fluid; treating the "spent" chromic acid with an alkali, alkaline carbonate
or alkaline salt, so as to recover the metal employed or the oxide of that metal;
and combining the remainder of the "spent" chromic acid with the sulphate of lead
or other sulphate obtained in the first step, in order to recover the original chromate
of lead or other chromate employed.
! 11. The method comprising the following steps: Treating a chromate of lead or
other chromate with sulphuric acid, so as to separate it into two parts, one of which
contains chromic acid, and the other sulphate of lead or other sulphate; using the
chromic acid thus obtained alone or in combination with an acid or acid salt, in a
battery fluid; treating the "spent" chromic acid with an alkali, alkaline carbonate
or alkaline salt, drying and igniting, and treating so as to recover the metal
employed or the oxide of that metal; and combining the remainder of the "spent
chromic acid with the sulphate of lead or other sulphate obtained in the first step,
in order to recover the original chromate of lead or other chromate employed.
"
12. The method comprising the following steps: Treating a chromate of lead
or other chromate with sulphuric acid, so as to separate it into two parts, one
of which contains chromic acid and the other sulphate of lead or other sulphate;
using the chromic acid thus obtained alone or in combination with an acid or acid
salt, in a battery fluid; treating the "spent " chromic acid with carbonate of
potash so as to recover the metal employed or the oxide of that metal; and
combining the remainder of the "spent" chromic acid with the sulphate of lead or
other sulphate obtained in the first step, in order to recover the original chromate
of lead or other chromate employed.
13. The method comprising the following steps: Treating a chromate of lead
or other chromate with sulphuric acid, so as to separate it into two parts, one of
which contains chromic acid and the other sulphate of lead or other sulphate;
using the chromic acid thus obtained alone or in combination with an acid or acid
salt, in a battery fluid; treating the "spent" chromic acid with carbonate of potash,
drying, igniting and treating so as to recover the metal employed or the oxide of
that metal; and combining the remainder of the "spent" chromic acid with the
sulphate of lead or sulphate obtained in the first step; in order to recover the
original chromate of lead or other chromate employed.
14. The method comprising the following steps: Treating a chromate of lead or
other chromate with sulphuric acid so as to separate it into two parts, one containing
chromic acid and the other sulphate of lead or other sulphate; using the chromic
acid thus obtained alone or in combination with an acid or an acid salt, in a battery
fluid; treating the "spent" chromic acid with carbonate of potash, drying, igniting
and treating so as to recover the metal employed or the oxide of that metal;
combining the remainder of the "spent" chromic acid with the sulphate of lead or
other sulphate obtained in the first step. to recover the original chromate of lead
or other chromate employed, and to leave sulphate of potash as a residuum; and
finally precipitating the sulphate of potash with carbonate of lime, to obtain sulphate
of lime and carbonate of potash.
15. The method of recovering the zinc consumed in a primary battery consisting
of combining the "spent" depolarizing fluid with an alkali, alkali carbonate, or
alkali salt, drying, igniting and separating out the zinc or its oxide.
16. The method of recovering the zinc consumed in a primary battery consisting
of combining the "spent" depolarizing fluid with carbonate of potash, drying,
igniting and separating out the zinc, or its oxide.
17. The method of recovering the zinc consumed in a chromic acid battery,
consisting of combining the "spent" chromic and other acids with carbonate of
potash, drying, igniting and separating out the zinc or its oxide.
18. The method comprising the following steps: Treating a salt with an acid, so
as to separate it into two parts, one of which contains the depolarizing element;

page_text: using the depolarizing element thus obtained, alone or in combination with an acid
or acid salt, in a battery fluid; and treating the "spent" depolarizing fluit with an
alkali, alkaline carbonate or alkaline salt, or with the unused part of the salt
obtained in the first step, and separating out the metal employed or the oxide of
the metal, to recover the original salt employed.
19. The method comprising the following steps: Treating a salt with an acid so
as to separate it into two parts, one of which contains the depolarizing element ;
using the depolarizing element thus obtained, alone or in combination with an acid
or acid salt, in a battery fluid; and treating the "spent" depolarizing fluid with an
alkali, alkaline carbonate or alkaline salt, or with the unused part of the salt
obtained in the first step, drying and igniting, and separating out the metal employed
or the oxide of that metal, to recover the original salt employed.
20. The method comprising the following steps: Treating a chromate of lime,
or other alkali chromate, with an acid, so as to separate it into two parts, one of
which contains chromic acid; using the chromic acid thus obtained, alone or in
combination with an acid or acid sult, in a battery fluid; and treating the "spent"
chromic acid with an alkali, alkaline carbonate or alkaline salt, or with the unused
part of the chromate of lime or other alkaline chromate obtained in the first step,
and separating out the metal employed, or the oxide of that metal, to recover the
original chromate of lime or other chromate employed.
21. The method comprising the following steps: Treating a chromate of lime
or other alkaline chromate with sulphuric acid, so as to separate it into two parts,
one of which contains chromic acid, and the other sulphate of lime or other sulphate;
using the chromic acid thus obtained alone or in combination with an acid or acid
salt, in a battery fluid; and treating the "spent" chromic acid with an alkali,
alkaline carbonate or alkaline salt, or with the sulphate of lime or other sulphate
obtained in the first step, and separating out the metal employed or the oxide
of that metal, to recover the original chromate of lime or other chromate
employed.
"
22. The method comprising the following steps: Treating a chromate of lime
with sulphuric acid, so as to separate it into two parts, one of which contains chromic
acid and the other sulphate of lime; using the chromic acid thus obtained, alone or
in combination with an acid or acid salt, in a battery fluid; and treating the "spent
chromic acid with carbonate of lime, drying and igniting, and separating out the
metal employed or the oxide of that metal, to recover the chromate of lime originally
employed.
Dated this 90th day of Santambou 1901
HENRY H. LEIGH,
Chartered Patent Agent.