How to delete a file in QNX4 format when a CF card is mounted as read-only in Linux?

Recently, the DMA device of our lab is broken and the suspected problem is in the CF card which is in QNX4 format. I want to delete a file named 'calforce.dat' and recreate it by calibrating the device.

I mount the CF card in my device and got this result:

famer@iphyer:~$ sudo mount -t qnx4 /dev/sdb1 /mnt/
[sudo] password for famer: 
mount: warning: /mnt/ seems to be mounted read-only.
famer@iphyer:~$ cd /mnt
famer@iphyer:/mnt$ ls
bin           calfreq.dat  dma           dmasav.dat  fit2.dat      qgui
caldyn.dat    calraw.dat   dma21cfr.dat  dmausr.dat  lib           sbin
calfgen.dat   calres.dat   dmaclamp.dat  etc         license.dat   test_enu.str
calfgres.dat  calrpt.txt   dmaid.dat     exit_case   loader        usr
calforce.dat  devi-ads     dmamfg.dat    fit1.dat    loader_image

I want to delete the 'calforce.dat' file but all commands like writing and deleting have been denied by the read-only system.

Commands like:

famer@iphyer:/mnt$ sudo mount -o remount,rw /dev/sdb1
[sudo] password for famer: 
mount: warning: /mnt seems to be mounted read-only.

do not give any results.

How can I solve it?

Or, alternatively, can I can copy the files out of the CF card to new CF card. Do I need to format a new card before I can use it? Can I simply use something like GPart or fdisk to realize it?

========================================================================== Below is what I followed Gilles' suggestion below is what the kernel log since I insert the CF card.

Dec 15 12:51:13 MG kernel: [ 1477.242018] usb 1-1.1: new high-speed USB device number 3 using ehci-pci
Dec 15 12:51:13 MG kernel: [ 1477.349093] usb 1-1.1: New USB device found, idVendor=0bda, idProduct=0158
Dec 15 12:51:13 MG kernel: [ 1477.349099] usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Dec 15 12:51:13 MG kernel: [ 1477.349102] usb 1-1.1: Product: USB2.0-CRW
Dec 15 12:51:13 MG kernel: [ 1477.349105] usb 1-1.1: Manufacturer: Generic
Dec 15 12:51:13 MG kernel: [ 1477.349107] usb 1-1.1: SerialNumber: 20060413092100000
Dec 15 12:51:14 MG kernel: [ 1477.787682] usbcore: registered new interface driver usb-storage
Dec 15 12:51:14 MG kernel: [ 1477.816933] ums-realtek 1-1.1:1.0: USB Mass Storage device detected
Dec 15 12:51:14 MG kernel: [ 1477.818979] scsi6 : usb-storage 1-1.1:1.0
Dec 15 12:51:14 MG kernel: [ 1477.819043] usbcore: registered new interface driver ums-realtek
Dec 15 12:51:15 MG kernel: [ 1478.830020] scsi 6:0:0:0: Direct-Access     Generic- Multi-Card       1.00 PQ: 0 ANSI: 0 CCS
Dec 15 12:51:15 MG kernel: [ 1478.831859] sd 6:0:0:0: Attached scsi generic sg2 type 0
Dec 15 12:51:16 MG kernel: [ 1479.669070] sd 6:0:0:0: [sdb] 264096 512-byte logical blocks: (135 MB/128 MiB)
Dec 15 12:51:16 MG kernel: [ 1479.670566] sd 6:0:0:0: [sdb] Write Protect is off
Dec 15 12:51:16 MG kernel: [ 1479.670572] sd 6:0:0:0: [sdb] Mode Sense: 03 00 00 00
Dec 15 12:51:16 MG kernel: [ 1479.672012] sd 6:0:0:0: [sdb] No Caching mode page found
Dec 15 12:51:16 MG kernel: [ 1479.672016] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Dec 15 12:51:16 MG kernel: [ 1479.678399] sd 6:0:0:0: [sdb] No Caching mode page found
Dec 15 12:51:16 MG kernel: [ 1479.678404] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Dec 15 12:51:16 MG kernel: [ 1479.679767]  sdb: sdb1
Dec 15 12:51:16 MG kernel: [ 1479.683276] sd 6:0:0:0: [sdb] No Caching mode page found
Dec 15 12:51:16 MG kernel: [ 1479.683290] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Dec 15 12:51:16 MG kernel: [ 1479.683292] sd 6:0:0:0: [sdb] Attached SCSI removable disk
Dec 15 12:52:17 MG kernel: [ 1541.078472] QNX4 filesystem 0.2.3 registered.

Does it help?