Abstract: An improvement to the chloride process of making titanium dioxide. By recycling some of the cyclone dust, the yield in the chlorination of titanium-containing raw materials can be increased. In order to prevent silica accumulation in the fluidized bed, the cyclone dust is divided into two fractions. An economic solution is described of a single-stage separation of the cyclone dust in a hydrocyclone, the majority of the titanium dioxide occurring in the hydrocyclone underflow, although the separation is not sharp. By grinding and drying the solids from the hydrocyclone underflow, the titanium dioxide particles returned to the lower region of the fluidized-bed reactor are rapidly chlorinated, while the quartz and coke particles are rapidly discharged again from the fluid bed, so that no silica contamination occurs.
Abstract: The hydrolysis of carbonyl sulfide is substantially improved by utilizing titanium dioxide particles as a catalyst. It is especially favorable, if the titanium dioxide particle are sintered and treated with sodium hydroxide or sodium aluminate. Through such a treatment, the catalyst can be regenerated and reutilized.
Abstract: In the preparation of metal chlorides from their elements to be used as additives in processes of making titanium dioxide by the chloride process, a titanium tetrachloride stream is directed to sweep over the lined inner wall of a metal chloride generator to act as a protective film, which considerably increases the life of the generator. Furthermore, the titanium tetrachloride is further heated, which is highly desirable in the chloride process. When the titanium tetrachloride is optionally conducted in advance through ducts in the lining of the inner walls of the metal chloride generator, its temperature can be further raised.
Abstract: In the preparation of a suspension with a high content of titanium dioxide, which has been produced according to the chloride process, a finely divided titanium dioxide is slurried, in unflocculated condition without use of a dispersing agent, dechlorinated and then filtered. The content of multivalent anions can be controlled in the slurry before the filtration through suitable dechlorinating agents, particularly hydrogen peroxide and/or sodium hydrogen sulfite, and thereby the solid content in the filter cake and the consistency of the filter cake are advantageously influenced. If, on one hand, no or only few multivalent anions are present, a thixotropic filter cake with a high solids content is obtained in a pressure filtration. The filter cake is converted into a titanium dioxide suspension with a high solids content through feeding into a titanium dioxide suspension to which a dispersing agent has been added.
January 30, 1995
Date of Patent:
July 30, 1996
Siegfried Blumel, Achim Hartmann, Hans Thumm, Hans-Hermann Luginsland, Franz Rosendahl
Abstract: Small quantities of an alkali metal salt control additive, along with the addition of a rutile promotion additive, preferably aluminum trichloride as ruffle promoter, is added in the oxidation of titanium tetrachloride into the titanium dioxide burner reaction zone. Metal used to make aluminum trichloride is introduced into a aluminum chloride generator reactor in a main branch, and the alkali metal salt is introduced in a subsidiary branch in a controlled addition provided by a "dilution" mixture of the salt in aluminum powder and preferably by applying additional agents which improve the flee-flowing properties of the mixture such as, for example, anhydrous potassium oleate.
Abstract: Subpigmentary titanium dioxide with decreased photoactivity is produced if known ions for increasing photostability in titanium dioxide pigments are not deposited on the surface of the subpigmentary particles, but instead are included intracrystallinely in the pigment particle (i.e., doped). In a preferred process for preparation of doped subpigmentary titanium dioxide particles, an acid solution containing the dopant is added in two stages to a suspension of subpigmentary titanium dioxide.
Abstract: The production of titanium dioxide by the sulphate process generates waste substances such as the wash filtrates, which are formed in the washing of titanium dioxide hydrate, and waste gases which contain sulphur dioxide. In this improved process the wash filtrate is used to remove the sulphur dioxide from the waste gas while the sulphuric acid content of the wash filtrate is raised and the sulphuric acid-containing process solution thus obtained is used within the scope of the titanium dioxide production process. The waste gas and the wash filtrate are passed countercurrently through a series of several washing steps and are contacted with each other by introducing the wash liquid into the waste gas in a finely divided form in scrub towers. The sulphuric acid content of the washing fluid is stepwise changed from washing stage to washing stage. The sulphur dioxide content of the waste gas is reduced to values that may be discharged into the ambient atmosphere.
Abstract: A process for purifying an acidic technical-grade iron chloride solution formed from cyclone dust from the production of TiO.sub.2 in accordance with the chloride process by adjusting the pH with a first neutralizing agent and thereafter introducing the pH adjusted solution in a controlled manner into a solution containing a second neutralizing agent. In this process undesired ions which are to be separated, such as chromium, vanadium, zirconium and/or niobium, precipitate in the form of efficiently filterable hydroxides which can be separated industrially under economical conditions by filtration. The filter cake is non-hazardous and can safely be disposed of by dumping. Calcium carbonate is the preferred neutralizing agent, and the pH adjustment may also advantageously be effected by using scrap iron or by using iron sinters with reduction of any Fe(III) ions before the second neutralization step.
Abstract: In order to treat metal chlorides obtained in the form of dust collector solids in the production of titanium dioxide by the chloride process, the inert constituents, especially particulate coke, is separated then the metals are selectively precipitated and a maturing phase under oxidative conditions is provided for. The residue consisting of metal hydroxides is also not thixotropic in the absence of inerts. As a result, the material to be deposited has been cut in half.
Abstract: Disclosed is a process for treating waste sulfuric acid generated from a process for producing titanium dioxide pigment by treating titanium slag with sulfuric acid. The waste acid is treated in a first step with a calcium-containing material to produce a gypsum suspension which is filtered and from which a filtrate is recovered. The filtrate is treated in a second step with a calcium-containing substance and clarification solids from the treatment of the titanium slag with sulfuric acid. A precipitate is produced in this second step which is subsequently filtered. The precipitate is suitable for disposal in a landfill.
Abstract: For economical and assured separation of chromium, vanadium and titanium ions from acidic waste waters, which accrue in great quantities in preparation of titanium dioxide, the pH is first raised to around a value of 3 by addition of dolomite brick powder. Directly thereafter, the pH is fine tuned into the range of 4.3 to 4.7 through addition of calcium hydroxide and/or sodium hydroxide, and the hydroxides are separated with the aid of a flocculating agent. Since iron ions and calcium ions remain mainly dissolved in the waste water through such selective precipitation, only a relatively small volume of slush has to be disposed of.
Abstract: This invention provides a process for the recovery of purified ferrous chloride resulting as a by-product during the production of titanium dioxide by the chloride process. The process involves a two-step cooling of a filtered solution containing ferrous chloride and other material in a manner to crystallize the ferrous chloride as a pure product. Such product can then be sold commercially including to companies involved in the waste water treatment business.
Abstract: A novel method of adapting Fibonacci number weighting to raw binary code data of variable length to use the code as a fixed length code by using only those code sequences with a fixed number of cells rather than a fixed number of bits, converting the code to a continuous numerical sequence useful particularly for linear media and data transmission. Encoder and decoder systems useful to enable storing or recording and reading or utilization of the Fibonacci code in bar code, magnetic and other media.
Abstract: This disclosure is concerned with automatically identifying authorized break, meal and other time intervals in check-out and check-in of employee timecards in time-recording systems and the like and accommodating for the same in computing total working hours in such systems.
Abstract: This disclosure is concerned with time-clock recording and computation that, through a novel clock track card and separate clock track and data channel optical reading, in cooperation with microprocessor calculation, storage and control, enables automating employee time and attendance and similar data in a format directly recordable on the card and also directly useable by payroll or other processing computers and the like.
March 13, 1979
Date of Patent:
May 26, 1981
Larry K. Baxter, Robert D. Cohen, Mark S. Ain, Sheldon P. Apsell